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Released 2022-04-28

- Fix type annotation for ``json.loads``, it accepts str or bytes.
- The ``--cert`` and ``--key`` options on ``flask run`` can be given
in either order. :issue:`4459`



Released on 2022-03-30

- Set the minimum required version of importlib_metadata to 3.6.0,
which is required on Python < 3.10. :issue:`4502`



Released 2022-03-28

- Drop support for Python 3.6. :pr:`4335`
- Update Click dependency to >= 8.0. :pr:`4008`
- Remove previously deprecated code. :pr:`4337`

- The CLI does not pass ``script_info`` to app factory functions.
- ``config.from_json`` is replaced by
``config.from_file(name, load=json.load)``.
- ``json`` functions no longer take an ``encoding`` parameter.
- ``safe_join`` is removed, use ``werkzeug.utils.safe_join``
- ``total_seconds`` is removed, use ``timedelta.total_seconds``
- The same blueprint cannot be registered with the same name. Use
``name=`` when registering to specify a unique name.
- The test client's ``as_tuple`` parameter is removed. Use
``response.request.environ`` instead. :pr:`4417`

- Some parameters in ``send_file`` and ``send_from_directory`` were
renamed in 2.0. The deprecation period for the old names is extended
to 2.2. Be sure to test with deprecation warnings visible.

- ``attachment_filename`` is renamed to ``download_name``.
- ``cache_timeout`` is renamed to ``max_age``.
- ``add_etags`` is renamed to ``etag``.
- ``filename`` is renamed to ``path``.

- The ``RequestContext.g`` property is deprecated. Use ``g`` directly
or ``AppContext.g`` instead. :issue:`3898`
- ``copy_current_request_context`` can decorate async functions.
- The CLI uses ``importlib.metadata`` instead of ``setuptools`` to
load command entry points. :issue:`4419`
- Overriding ```` will not cause an error on redirect.
- Add an ``--exclude-patterns`` option to the ``flask run`` CLI
command to specify patterns that will be ignored by the reloader.
- When using lazy loading (the default with the debugger), the Click
context from the ``flask run`` command remains available in the
loader thread. :issue:`4460`
- Deleting the session cookie uses the ``httponly`` flag.
- Relax typing for ``errorhandler`` to allow the user to use more
precise types and decorate the same function multiple times.
:issue:`4095, 4295, 4297`
- Fix typing for ``__exit__`` methods for better compatibility with
``ExitStack``. :issue:`4474`
- From Werkzeug, for redirect responses the ``Location`` header URL
will remain relative, and exclude the scheme and domain, by default.
- Add ``Config.from_prefixed_env()`` to load config values from
environment variables that start with ``FLASK_`` or another prefix.
This parses values as JSON by default, and allows setting keys in
nested dicts. :pr:`4479`



Released 2022-02-14

- The test client's ``as_tuple`` parameter is deprecated and will be
removed in Werkzeug 2.1. It is now also deprecated in Flask, to be
removed in Flask 2.1, while remaining compatible with both in
2.0.x. Use ``response.request.environ`` instead. :pr:`4341`
- Fix type annotation for ``errorhandler`` decorator. :issue:`4295`
- Revert a change to the CLI that caused it to hide ``ImportError``
tracebacks when importing the application. :issue:`4307`
- ``app.json_encoder`` and ``json_decoder`` are only passed to
``dumps`` and ``loads`` if they have custom behavior. This improves
performance, mainly on PyPy. :issue:`4349`
- Clearer error message when ``after_this_request`` is used outside a
request context. :issue:`4333`



Released 2021-10-04

- Fix type annotation for ``teardown_*`` methods. :issue:`4093`
- Fix type annotation for ``before_request`` and ``before_app_request``
decorators. :issue:`4104`
- Fixed the issue where typing requires template global
decorators to accept functions with no arguments. :issue:`4098`
- Support View and MethodView instances with async handlers. :issue:`4112`
- Enhance typing of ``app.errorhandler`` decorator. :issue:`4095`
- Fix registering a blueprint twice with differing names. :issue:`4124`
- Fix the type of ``static_folder`` to accept ``pathlib.Path``.
- ``jsonify`` handles ``decimal.Decimal`` by encoding to ``str``.
- Correctly handle raising deferred errors in CLI lazy loading.
- The CLI loader handles ``**kwargs`` in a ``create_app`` function.
- Fix the order of ``before_request`` and other callbacks that trigger
before the view returns. They are called from the app down to the
closest nested blueprint. :issue:`4229`



Released 2021-05-21

- Re-add the ``filename`` parameter in ``send_from_directory``. The
``filename`` parameter has been renamed to ``path``, the old name
is deprecated. :pr:`4019`
- Mark top-level names as exported so type checking understands
imports in user projects. :issue:`4024`
- Fix type annotation for ``g`` and inform mypy that it is a namespace
object that has arbitrary attributes. :issue:`4020`
- Fix some types that weren't available in Python 3.6.0. :issue:`4040`
- Improve typing for ``send_file``, ``send_from_directory``, and
``get_send_file_max_age``. :issue:`4044`, :pr:`4026`
- Show an error when a blueprint name contains a dot. The ``.`` has
special meaning, it is used to separate (nested) blueprint names and
the endpoint name. :issue:`4041`
- Combine URL prefixes when nesting blueprints that were created with
a ``url_prefix`` value. :issue:`4037`
- Roll back a change to the order that URL matching was done. The
URL is again matched after the session is loaded, so the session is
available in custom URL converters. :issue:`4053`
- Re-add deprecated ``Config.from_json``, which was accidentally
removed early. :issue:`4078`
- Improve typing for some functions using ``Callable`` in their type
signatures, focusing on decorator factories. :issue:`4060`
- Nested blueprints are registered with their dotted name. This allows
different blueprints with the same name to be nested at different
locations. :issue:`4069`
- ``register_blueprint`` takes a ``name`` option to change the
(pre-dotted) name the blueprint is registered with. This allows the
same blueprint to be registered multiple times with unique names for
``url_for``. Registering the same blueprint with the same name
multiple times is deprecated. :issue:`1091`
- Improve typing for ``stream_with_context``. :issue:`4052`



Released 2021-05-11

- Drop support for Python 2 and 3.5.
- Bump minimum versions of other Pallets projects: Werkzeug >= 2,
Jinja2 >= 3, MarkupSafe >= 2, ItsDangerous >= 2, Click >= 8. Be sure
to check the change logs for each project. For better compatibility
with other applications (e.g. Celery) that still require Click 7,
there is no hard dependency on Click 8 yet, but using Click 7 will
trigger a DeprecationWarning and Flask 2.1 will depend on Click 8.
- JSON support no longer uses simplejson. To use another JSON module,
override ``app.json_encoder`` and ``json_decoder``. :issue:`3555`
- The ``encoding`` option to JSON functions is deprecated. :pr:`3562`
- Passing ``script_info`` to app factory functions is deprecated. This
was not portable outside the ``flask`` command. Use
``click.get_current_context().obj`` if it's needed. :issue:`3552`
- The CLI shows better error messages when the app failed to load
when looking up commands. :issue:`2741`
- Add :meth:`sessions.SessionInterface.get_cookie_name` to allow
setting the session cookie name dynamically. :pr:`3369`
- Add :meth:`Config.from_file` to load config using arbitrary file
loaders, such as ``toml.load`` or ``json.load``.
:meth:`Config.from_json` is deprecated in favor of this. :pr:`3398`
- The ``flask run`` command will only defer errors on reload. Errors
present during the initial call will cause the server to exit with
the traceback immediately. :issue:`3431`
- :func:`send_file` raises a :exc:`ValueError` when passed an
:mod:`io` object in text mode. Previously, it would respond with
200 OK and an empty file. :issue:`3358`
- When using ad-hoc certificates, check for the cryptography library
instead of PyOpenSSL. :pr:`3492`
- When specifying a factory function with ``FLASK_APP``, keyword
argument can be passed. :issue:`3553`
- When loading a ``.env`` or ``.flaskenv`` file, the current working
directory is no longer changed to the location of the file.
- When returning a ``(response, headers)`` tuple from a view, the
headers replace rather than extend existing headers on the response.
For example, this allows setting the ``Content-Type`` for
``jsonify()``. Use ``response.headers.extend()`` if extending is
desired. :issue:`3628`
- The ``Scaffold`` class provides a common API for the ``Flask`` and
``Blueprint`` classes. ``Blueprint`` information is stored in
attributes just like ``Flask``, rather than opaque lambda functions.
This is intended to improve consistency and maintainability.
- Include ``samesite`` and ``secure`` options when removing the
session cookie. :pr:`3726`
- Support passing a ``pathlib.Path`` to ``static_folder``. :pr:`3579`
- ``send_file`` and ``send_from_directory`` are wrappers around the
implementations in ``werkzeug.utils``. :pr:`3828`
- Some ``send_file`` parameters have been renamed, the old names are
deprecated. ``attachment_filename`` is renamed to ``download_name``.
``cache_timeout`` is renamed to ``max_age``. ``add_etags`` is
renamed to ``etag``. :pr:`3828, 3883`
- ``send_file`` passes ``download_name`` even if
``as_attachment=False`` by using ``Content-Disposition: inline``.
- ``send_file`` sets ``conditional=True`` and ``max_age=None`` by
default. ``Cache-Control`` is set to ``no-cache`` if ``max_age`` is
not set, otherwise ``public``. This tells browsers to validate
conditional requests instead of using a timed cache. :pr:`3828`
- ``helpers.safe_join`` is deprecated. Use
``werkzeug.utils.safe_join`` instead. :pr:`3828`
- The request context does route matching before opening the session.
This could allow a session interface to change behavior based on
``request.endpoint``. :issue:`3776`
- Use Jinja's implementation of the ``|tojson`` filter. :issue:`3881`
- Add route decorators for common HTTP methods. For example,
``"/login")`` is a shortcut for
``app.route("/login", methods=["POST"])``. :pr:`3907`
- Support async views, error handlers, before and after request, and
teardown functions. :pr:`3412`
- Support nesting blueprints. :issue:`593, 1548`, :pr:`3923`
- Set the default encoding to "UTF-8" when loading ``.env`` and
``.flaskenv`` files to allow to use non-ASCII characters. :issue:`3931`
- ``flask shell`` sets up tab and history completion like the default
``python`` shell if ``readline`` is installed. :issue:`3941`
- ``helpers.total_seconds()`` is deprecated. Use
``timedelta.total_seconds()`` instead. :pr:`3962`
- Add type hinting. :pr:`3973`.



Released 2021-05-13

- Update ``static_folder`` to use ``_compat.fspath`` instead of
``os.fspath`` to continue supporting Python < 3.6 :issue:`4050`



Released 2021-05-13

- Set maximum versions of Werkzeug, Jinja, Click, and ItsDangerous.
- Re-add support for passing a ``pathlib.Path`` for ``static_folder``.



Released 2020-04-03

- Work around an issue when running the ``flask`` command with an
external debugger on Windows. :issue:`3297`
- The static route will not catch all URLs if the ``Flask``
``static_folder`` argument ends with a slash. :issue:`3452`



Released 2019-07-08

- The ``flask.json_available`` flag was added back for compatibility
with some extensions. It will raise a deprecation warning when used,
and will be removed in version 2.0.0. :issue:`3288`



Released 2019-07-04

- Bump minimum Werkzeug version to >= 0.15.
- Drop support for Python 3.4.
- Error handlers for ``InternalServerError`` or ``500`` will always be
passed an instance of ``InternalServerError``. If they are invoked
due to an unhandled exception, that original exception is now
available as ``e.original_exception`` rather than being passed
directly to the handler. The same is true if the handler is for the
base ``HTTPException``. This makes error handler behavior more
consistent. :pr:`3266`

- :meth:`Flask.finalize_request` is called for all unhandled
exceptions even if there is no ``500`` error handler.

- :attr:`Flask.logger` takes the same name as
:attr:`` (the value passed as
``Flask(import_name)``. This reverts 1.0's behavior of always
logging to ``""``, in order to support multiple apps in the
same process. A warning will be shown if old configuration is
detected that needs to be moved. :issue:`2866`
- :meth:`flask.RequestContext.copy` includes the current session
object in the request context copy. This prevents ``session``
pointing to an out-of-date object. :issue:`2935`
- Using built-in RequestContext, unprintable Unicode characters in
Host header will result in a HTTP 400 response and not HTTP 500 as
previously. :pr:`2994`
- :func:`send_file` supports :class:`~os.PathLike` objects as
described in PEP 0519, to support :mod:`pathlib` in Python 3.
- :func:`send_file` supports :class:`~io.BytesIO` partial content.
- :func:`open_resource` accepts the "rt" file mode. This still does
the same thing as "r". :issue:`3163`
- The :attr:`MethodView.methods` attribute set in a base class is used
by subclasses. :issue:`3138`
- :attr:`Flask.jinja_options` is a ``dict`` instead of an
``ImmutableDict`` to allow easier configuration. Changes must still
be made before creating the environment. :pr:`3190`
- Flask's ``JSONMixin`` for the request and response wrappers was
moved into Werkzeug. Use Werkzeug's version with Flask-specific
support. This bumps the Werkzeug dependency to >= 0.15.
- The ``flask`` command entry point is simplified to take advantage
of Werkzeug 0.15's better reloader support. This bumps the Werkzeug
dependency to >= 0.15. :issue:`3022`
- Support ``static_url_path`` that ends with a forward slash.
- Support empty ``static_folder`` without requiring setting an empty
``static_url_path`` as well. :pr:`3124`
- :meth:`jsonify` supports :class:`dataclasses.dataclass` objects.
- Allow customizing the :attr:`Flask.url_map_class` used for routing.
- The development server port can be set to 0, which tells the OS to
pick an available port. :issue:`2926`
- The return value from :meth:`cli.load_dotenv` is more consistent
with the documentation. It will return ``False`` if python-dotenv is
not installed, or if the given path isn't a file. :issue:`2937`
- Signaling support has a stub for the ``connect_via`` method when
the Blinker library is not installed. :pr:`3208`
- Add an ``--extra-files`` option to the ``flask run`` CLI command to
specify extra files that will trigger the reloader on change.
- Allow returning a dictionary from a view function. Similar to how
returning a string will produce a ``text/html`` response, returning
a dict will call ``jsonify`` to produce a ``application/json``
response. :pr:`3111`
- Blueprints have a ``cli`` Click group like ``app.cli``. CLI commands
registered with a blueprint will be available as a group under the
``flask`` command. :issue:`1357`.
- When using the test client as a context manager (``with client:``),
all preserved request contexts are popped when the block exits,
ensuring nested contexts are cleaned up correctly. :pr:`3157`
- Show a better error message when the view return type is not
supported. :issue:`3214`
- ``flask.testing.make_test_environ_builder()`` has been deprecated in
favour of a new class ``flask.testing.EnvironBuilder``. :pr:`3232`
- The ``flask run`` command no longer fails if Python is not built
with SSL support. Using the ``--cert`` option will show an
appropriate error message. :issue:`3211`
- URL matching now occurs after the request context is pushed, rather
than when it's created. This allows custom URL converters to access
the app and request contexts, such as to query a database for an id.



Released 2019-07-04

- The key information for ``BadRequestKeyError`` is no longer cleared
outside debug mode, so error handlers can still access it. This
requires upgrading to Werkzeug 0.15.5. :issue:`3249`
- ``send_file`` url quotes the ":" and "/" characters for more
compatible UTF-8 filename support in some browsers. :issue:`3074`
- Fixes for PEP451 import loaders and pytest 5.x. :issue:`3275`
- Show message about dotenv on stderr instead of stdout. :issue:`3285`



Released 2019-05-17

- :func:`send_file` encodes filenames as ASCII instead of Latin-1
(ISO-8859-1). This fixes compatibility with Gunicorn, which is
stricter about header encodings than PEP 3333. :issue:`2766`
- Allow custom CLIs using ``FlaskGroup`` to set the debug flag without
it always being overwritten based on environment variables.
- ``flask --version`` outputs Werkzeug's version and simplifies the
Python version. :pr:`2825`
- :func:`send_file` handles an ``attachment_filename`` that is a
native Python 2 string (bytes) with UTF-8 coded bytes. :issue:`2933`
- A catch-all error handler registered for ``HTTPException`` will not
handle ``RoutingException``, which is used internally during
routing. This fixes the unexpected behavior that had been introduced
in 1.0. :pr:`2986`
- Passing the ``json`` argument to ``app.test_client`` does not
push/pop an extra app context. :issue:`2900`



Released 2018-05-02

- Fix more backwards compatibility issues with merging slashes between
a blueprint prefix and route. :pr:`2748`
- Fix error with ``flask routes`` command when there are no routes.



Released 2018-04-29

- Fix registering partials (with no ``__name__``) as view functions.
- Don't treat lists returned from view functions the same as tuples.
Only tuples are interpreted as response data. :issue:`2736`
- Extra slashes between a blueprint's ``url_prefix`` and a route URL
are merged. This fixes some backwards compatibility issues with the
change in 1.0. :issue:`2731`, :issue:`2742`
- Only trap ``BadRequestKeyError`` errors in debug mode, not all
``BadRequest`` errors. This allows ``abort(400)`` to continue
working as expected. :issue:`2735`
- The ``FLASK_SKIP_DOTENV`` environment variable can be set to ``1``
to skip automatically loading dotenv files. :issue:`2722`



Released 2018-04-26

- Python 2.6 and 3.3 are no longer supported.
- Bump minimum dependency versions to the latest stable versions:
Werkzeug >= 0.14, Jinja >= 2.10, itsdangerous >= 0.24, Click >= 5.1.
- Skip :meth:` <>` when a Flask application is run
from the command line. This avoids some behavior that was confusing
to debug.
- Change the default for :data:`JSONIFY_PRETTYPRINT_REGULAR` to
``False``. :func:`~json.jsonify` returns a compact format by
default, and an indented format in debug mode. :pr:`2193`
- :meth:`Flask.__init__ <Flask>` accepts the ``host_matching``
argument and sets it on :attr:`~Flask.url_map`. :issue:`1559`
- :meth:`Flask.__init__ <Flask>` accepts the ``static_host`` argument
and passes it as the ``host`` argument when defining the static
route. :issue:`1559`
- :func:`send_file` supports Unicode in ``attachment_filename``.
- Pass ``_scheme`` argument from :func:`url_for` to
:meth:`~Flask.handle_url_build_error`. :pr:`2017`
- :meth:`~Flask.add_url_rule` accepts the
``provide_automatic_options`` argument to disable adding the
``OPTIONS`` method. :pr:`1489`
- :class:`~views.MethodView` subclasses inherit method handlers from
base classes. :pr:`1936`
- Errors caused while opening the session at the beginning of the
request are handled by the app's error handlers. :pr:`2254`
- Blueprints gained :attr:`~Blueprint.json_encoder` and
:attr:`~Blueprint.json_decoder` attributes to override the app's
encoder and decoder. :pr:`1898`
- :meth:`Flask.make_response` raises ``TypeError`` instead of
``ValueError`` for bad response types. The error messages have been
improved to describe why the type is invalid. :pr:`2256`
- Add ``routes`` CLI command to output routes registered on the
application. :pr:`2259`
- Show warning when session cookie domain is a bare hostname or an IP
address, as these may not behave properly in some browsers, such as
Chrome. :pr:`2282`
- Allow IP address as exact session cookie domain. :pr:`2282`
- ``SESSION_COOKIE_DOMAIN`` is set if it is detected through
``SERVER_NAME``. :pr:`2282`
- Auto-detect zero-argument app factory called ``create_app`` or
``make_app`` from ``FLASK_APP``. :pr:`2297`
- Factory functions are not required to take a ``script_info``
parameter to work with the ``flask`` command. If they take a single
parameter or a parameter named ``script_info``, the
:class:`~cli.ScriptInfo` object will be passed. :pr:`2319`
- ``FLASK_APP`` can be set to an app factory, with arguments if
needed, for example ``'dev')``.
- ``FLASK_APP`` can point to local packages that are not installed in
editable mode, although ``pip install -e`` is still preferred.
- The :class:`~views.View` class attribute
:attr:`~views.View.provide_automatic_options` is set in
:meth:`~views.View.as_view`, to be detected by
:meth:`~Flask.add_url_rule`. :pr:`2316`
- Error handling will try handlers registered for ``blueprint, code``,
``app, code``, ``blueprint, exception``, ``app, exception``.
- ``Cookie`` is added to the response's ``Vary`` header if the session
is accessed at all during the request (and not deleted). :pr:`2288`
- :meth:`~Flask.test_request_context` accepts ``subdomain`` and
``url_scheme`` arguments for use when building the base URL.
- Set :data:`APPLICATION_ROOT` to ``'/'`` by default. This was already
the implicit default when it was set to ``None``.
- :data:`TRAP_BAD_REQUEST_ERRORS` is enabled by default in debug mode.
``BadRequestKeyError`` has a message with the bad key in debug mode
instead of the generic bad request message. :pr:`2348`
- Allow registering new tags with
:class:`~json.tag.TaggedJSONSerializer` to support storing other
types in the session cookie. :pr:`2352`
- Only open the session if the request has not been pushed onto the
context stack yet. This allows :func:`~stream_with_context`
generators to access the same session that the containing view uses.
- Add ``json`` keyword argument for the test client request methods.
This will dump the given object as JSON and set the appropriate
content type. :pr:`2358`
- Extract JSON handling to a mixin applied to both the
:class:`Request` and :class:`Response` classes. This adds the
:meth:`~Response.is_json` and :meth:`~Response.get_json` methods to
the response to make testing JSON response much easier. :pr:`2358`
- Removed error handler caching because it caused unexpected results
for some exception inheritance hierarchies. Register handlers
explicitly for each exception if you want to avoid traversing the
MRO. :pr:`2362`
- Fix incorrect JSON encoding of aware, non-UTC datetimes. :pr:`2374`
- Template auto reloading will honor debug mode even even if
:attr:`~Flask.jinja_env` was already accessed. :pr:`2373`
- The following old deprecated code was removed. :issue:`2385`

- ``flask.ext`` - import extensions directly by their name instead
of through the ``flask.ext`` namespace. For example,
``import flask.ext.sqlalchemy`` becomes
``import flask_sqlalchemy``.
- ``Flask.init_jinja_globals`` - extend
:meth:`Flask.create_jinja_environment` instead.
- ``Flask.error_handlers`` - tracked by
:attr:`Flask.error_handler_spec`, use :meth:`Flask.errorhandler`
to register handlers.
- ``Flask.request_globals_class`` - use
:attr:`Flask.app_ctx_globals_class` instead.
- ``Flask.static_path`` - use :attr:`Flask.static_url_path`
- ``Request.module`` - use :attr:`Request.blueprint` instead.

- The :attr:`Request.json` property is no longer deprecated.
- Support passing a :class:`~werkzeug.test.EnvironBuilder` or ``dict``
to :meth:` <>`. :pr:`2412`
- The ``flask`` command and :meth:`` will load environment
variables from ``.env`` and ``.flaskenv`` files if python-dotenv is
installed. :pr:`2416`
- When passing a full URL to the test client, the scheme in the URL is
used instead of :data:`PREFERRED_URL_SCHEME`. :pr:`2430`
- :attr:`Flask.logger` has been simplified. ``LOGGER_NAME`` and
``LOGGER_HANDLER_POLICY`` config was removed. The logger is always
named ````. The level is only set on first access, it
doesn't check :attr:`Flask.debug` each time. Only one format is
used, not different ones depending on :attr:`Flask.debug`. No
handlers are removed, and a handler is only added if no handlers are
already configured. :pr:`2436`
- Blueprint view function names may not contain dots. :pr:`2450`
- Fix a ``ValueError`` caused by invalid ``Range`` requests in some
cases. :issue:`2526`
- The development server uses threads by default. :pr:`2529`
- Loading config files with ``silent=True`` will ignore
:data:`~errno.ENOTDIR` errors. :pr:`2581`
- Pass ``--cert`` and ``--key`` options to ``flask run`` to run the
development server over HTTPS. :pr:`2606`
- Added :data:`SESSION_COOKIE_SAMESITE` to control the ``SameSite``
attribute on the session cookie. :pr:`2607`
- Added :meth:`~flask.Flask.test_cli_runner` to create a Click runner
that can invoke Flask CLI commands for testing. :pr:`2636`
- Subdomain matching is disabled by default and setting
:data:`SERVER_NAME` does not implicitly enable it. It can be enabled
by passing ``subdomain_matching=True`` to the ``Flask`` constructor.
- A single trailing slash is stripped from the blueprint
``url_prefix`` when it is registered with the app. :pr:`2629`
- :meth:`Request.get_json` doesn't cache the result if parsing fails
when ``silent`` is true. :issue:`2651`
- :func:`Request.get_json` no longer accepts arbitrary encodings.
Incoming JSON should be encoded using UTF-8 per :rfc:`8259`, but
Flask will autodetect UTF-8, -16, or -32. :pr:`2691`
- Added :data:`MAX_COOKIE_SIZE` and :attr:`Response.max_cookie_size`
to control when Werkzeug warns about large cookies that browsers may
ignore. :pr:`2693`
- Updated documentation theme to make docs look better in small
windows. :pr:`2709`
- Rewrote the tutorial docs and example project to take a more
structured approach to help new users avoid common pitfalls.



Released 2020-02-10

- Pin Werkzeug to < 1.0.0. :issue:`3497`



Released 2018-04-29

- Repackage 0.12.3 to fix package layout issue. :issue:`2728`



Released 2018-04-26

- :func:`Request.get_json` no longer accepts arbitrary encodings.
Incoming JSON should be encoded using UTF-8 per :rfc:`8259`, but
Flask will autodetect UTF-8, -16, or -32. :issue:`2692`
- Fix a Python warning about imports when using ``python -m flask``.
- Fix a ``ValueError`` caused by invalid ``Range`` requests in some


Not secure

Released 2017-05-16

- Fix a bug in ``safe_join`` on Windows.


Not secure

Released 2017-03-31

- Prevent ``flask run`` from showing a ``NoAppException`` when an
``ImportError`` occurs within the imported application module.
- Fix encoding behavior of ``app.config.from_pyfile`` for Python 3.
- Use the ``SERVER_NAME`` config if it is present as default values
for ````. :issue:`2109`, :pr:`2152`
- Call ``ctx.auto_pop`` with the exception object instead of ``None``,
in the event that a ``BaseException`` such as ``KeyboardInterrupt``
is raised in a request handler.


Not secure

Released 2016-12-21, codename Punsch

- The cli command now responds to ``--version``.
- Mimetype guessing and ETag generation for file-like objects in
``send_file`` has been removed. :issue:`104`, :pr`1849`
- Mimetype guessing in ``send_file`` now fails loudly and doesn't fall
back to ``application/octet-stream``. :pr:`1988`
- Make ``flask.safe_join`` able to join multiple paths like
``os.path.join`` :pr:`1730`
- Revert a behavior change that made the dev server crash instead of
returning an Internal Server Error. :pr:`2006`
- Correctly invoke response handlers for both regular request
dispatching as well as error handlers.
- Disable logger propagation by default for the app logger.
- Add support for range requests in ``send_file``.
- ``app.test_client`` includes preset default environment, which can
now be directly set, instead of per ``client.get``.
- Fix crash when running under PyPy3. :pr:`1814`


Not secure

Released 2016-06-07

- Fixed a bug that prevented ``FLASK_APP=foobar/`` from
working. :pr:`1872`


Not secure

Released 2016-05-29, codename Absinthe

- Added support to serializing top-level arrays to
:func:`flask.jsonify`. This introduces a security risk in ancient
- Added before_render_template signal.
- Added ``**kwargs`` to :meth:`flask.Test.test_client` to support
passing additional keyword arguments to the constructor of
- Added ``SESSION_REFRESH_EACH_REQUEST`` config key that controls the
set-cookie behavior. If set to ``True`` a permanent session will be
refreshed each request and get their lifetime extended, if set to
``False`` it will only be modified if the session actually modifies.
Non permanent sessions are not affected by this and will always
expire if the browser window closes.
- Made Flask support custom JSON mimetypes for incoming data.
- Added support for returning tuples in the form ``(response,
headers)`` from a view function.
- Added :meth:`flask.Config.from_json`.
- Added :attr:`flask.Flask.config_class`.
- Added :meth:`flask.Config.get_namespace`.
- Templates are no longer automatically reloaded outside of debug
mode. This can be configured with the new ``TEMPLATES_AUTO_RELOAD``
config key.
- Added a workaround for a limitation in Python 3.3's namespace
- Added support for explicit root paths when using Python 3.3's
namespace packages.
- Added :command:`flask` and the ``flask.cli`` module to start the
local debug server through the click CLI system. This is recommended
over the old ```` method as it works faster and more
reliable due to a different design and also replaces
- Error handlers that match specific classes are now checked first,
thereby allowing catching exceptions that are subclasses of HTTP
exceptions (in ``werkzeug.exceptions``). This makes it possible for
an extension author to create exceptions that will by default result
in the HTTP error of their choosing, but may be caught with a custom
error handler if desired.
- Added :meth:`flask.Config.from_mapping`.
- Flask will now log by default even if debug is disabled. The log
format is now hardcoded but the default log handling can be disabled
through the ``LOGGER_HANDLER_POLICY`` configuration key.
- Removed deprecated module functionality.
- Added the ``EXPLAIN_TEMPLATE_LOADING`` config flag which when
enabled will instruct Flask to explain how it locates templates.
This should help users debug when the wrong templates are loaded.
- Enforce blueprint handling in the order they were registered for
template loading.
- Ported test suite to py.test.
- Deprecated ``request.json`` in favour of ``request.get_json()``.
- Add "pretty" and "compressed" separators definitions in jsonify()
method. Reduces JSON response size when
``JSONIFY_PRETTYPRINT_REGULAR=False`` by removing unnecessary white
space included by default after separators.
- JSON responses are now terminated with a newline character, because
it is a convention that UNIX text files end with a newline and some
clients don't deal well when this newline is missing. This came up
originally as a part of :pr:`1262`
- The automatically provided ``OPTIONS`` method is now correctly
disabled if the user registered an overriding rule with the
lowercase-version ``options``. :issue:`1288`
- ``flask.json.jsonify`` now supports the ```` type.
- Don't leak exception info of already caught exceptions to context
teardown handlers. :pr:`1393`
- Allow custom Jinja environment subclasses. :pr:`1422`
- Updated extension dev guidelines.
- ``flask.g`` now has ``pop()`` and ``setdefault`` methods.
- Turn on autoescape for ``flask.templating.render_template_string``
by default. :pr:`1515`
- ``flask.ext`` is now deprecated. :pr:`1484`
- ``send_from_directory`` now raises BadRequest if the filename is
invalid on the server OS. :pr:`1763`
- Added the ``JSONIFY_MIMETYPE`` configuration variable. :pr:`1728`
- Exceptions during teardown handling will no longer leave bad
application contexts lingering around.
- Fixed broken ``test_appcontext_signals()`` test case.
- Raise an :exc:`AttributeError` in :func:`flask.helpers.find_package`
with a useful message explaining why it is raised when a PEP 302
import hook is used without an ``is_package()`` method.
- Fixed an issue causing exceptions raised before entering a request
or app context to be passed to teardown handlers.
- Fixed an issue with query parameters getting removed from requests
in the test client when absolute URLs were requested.
- Made ``before_first_request`` into a decorator as intended.
- Fixed an etags bug when sending a file streams with a name.
- Fixed ``send_from_directory`` not expanding to the application root
path correctly.
- Changed logic of before first request handlers to flip the flag
after invoking. This will allow some uses that are potentially
dangerous but should probably be permitted.
- Fixed Python 3 bug when a handler from
``app.url_build_error_handlers`` reraises the ``BuildError``.


Not secure

Released 2013-06-14

- Fixed an issue where ``|tojson`` was not quoting single quotes which
made the filter not work properly in HTML attributes. Now it's
possible to use that filter in single quoted attributes. This should
make using that filter with angular.js easier.
- Added support for byte strings back to the session system. This
broke compatibility with the common case of people putting binary
data for token verification into the session.
- Fixed an issue where registering the same method twice for the same
endpoint would trigger an exception incorrectly.


Not secure

Released 2013-06-13, codename Limoncello

- Changed default cookie serialization format from pickle to JSON to
limit the impact an attacker can do if the secret key leaks.
- Added ``template_test`` methods in addition to the already existing
``template_filter`` method family.
- Added ``template_global`` methods in addition to the already
existing ``template_filter`` method family.
- Set the content-length header for x-sendfile.
- ``tojson`` filter now does not escape script blocks in HTML5
- ``tojson`` used in templates is now safe by default due. This was
allowed due to the different escaping behavior.
- Flask will now raise an error if you attempt to register a new
function on an already used endpoint.
- Added wrapper module around simplejson and added default
serialization of datetime objects. This allows much easier
customization of how JSON is handled by Flask or any Flask
- Removed deprecated internal ``flask.session`` module alias. Use
``flask.sessions`` instead to get the session module. This is not to
be confused with ``flask.session`` the session proxy.
- Templates can now be rendered without request context. The behavior
is slightly different as the ``request``, ``session`` and ``g``
objects will not be available and blueprint's context processors are
not called.
- The config object is now available to the template as a real global
and not through a context processor which makes it available even in
imported templates by default.
- Added an option to generate non-ascii encoded JSON which should
result in less bytes being transmitted over the network. It's
disabled by default to not cause confusion with existing libraries
that might expect ``flask.json.dumps`` to return bytes by default.
- ``flask.g`` is now stored on the app context instead of the request
- ``flask.g`` now gained a ``get()`` method for not erroring out on
non existing items.
- ``flask.g`` now can be used with the ``in`` operator to see what's
defined and it now is iterable and will yield all attributes stored.
- ``flask.Flask.request_globals_class`` got renamed to
``flask.Flask.app_ctx_globals_class`` which is a better name to what
it does since 0.10.
- ``request``, ``session`` and ``g`` are now also added as proxies to
the template context which makes them available in imported
templates. One has to be very careful with those though because
usage outside of macros might cause caching.
- Flask will no longer invoke the wrong error handlers if a proxy
exception is passed through.
- Added a workaround for chrome's cookies in localhost not working as
intended with domain names.
- Changed logic for picking defaults for cookie values from sessions
to work better with Google Chrome.
- Added ``message_flashed`` signal that simplifies flashing testing.
- Added support for copying of request contexts for better working
with greenlets.
- Removed custom JSON HTTP exception subclasses. If you were relying
on them you can reintroduce them again yourself trivially. Using
them however is strongly discouraged as the interface was flawed.
- Python requirements changed: requiring Python 2.6 or 2.7 now to
prepare for Python 3.3 port.
- Changed how the teardown system is informed about exceptions. This
is now more reliable in case something handles an exception halfway
through the error handling process.
- Request context preservation in debug mode now keeps the exception
information around which means that teardown handlers are able to
distinguish error from success cases.
- Added the ``JSONIFY_PRETTYPRINT_REGULAR`` configuration variable.
- Flask now orders JSON keys by default to not trash HTTP caches due
to different hash seeds between different workers.
- Added ``appcontext_pushed`` and ``appcontext_popped`` signals.
- The builtin run method now takes the ``SERVER_NAME`` into account
when picking the default port to run on.
- Added ``flask.request.get_json()`` as a replacement for the old
``flask.request.json`` property.


Not secure

Released 2012-07-01, codename Campari

- The :func:`flask.Request.on_json_loading_failed` now returns a JSON
formatted response by default.
- The :func:`flask.url_for` function now can generate anchors to the
generated links.
- The :func:`flask.url_for` function now can also explicitly generate
URL rules specific to a given HTTP method.
- Logger now only returns the debug log setting if it was not set
- Unregister a circular dependency between the WSGI environment and
the request object when shutting down the request. This means that
environ ``werkzeug.request`` will be ``None`` after the response was
returned to the WSGI server but has the advantage that the garbage
collector is not needed on CPython to tear down the request unless
the user created circular dependencies themselves.
- Session is now stored after callbacks so that if the session payload
is stored in the session you can still modify it in an after request
- The :class:`flask.Flask` class will avoid importing the provided
import name if it can (the required first parameter), to benefit
tools which build Flask instances programmatically. The Flask class
will fall back to using import on systems with custom module hooks,
e.g. Google App Engine, or when the import name is inside a zip
archive (usually a .egg) prior to Python 2.7.
- Blueprints now have a decorator to add custom template filters
application wide, :meth:`flask.Blueprint.app_template_filter`.
- The Flask and Blueprint classes now have a non-decorator method for
adding custom template filters application wide,
:meth:`flask.Flask.add_template_filter` and
- The :func:`flask.get_flashed_messages` function now allows rendering
flashed message categories in separate blocks, through a
``category_filter`` argument.
- The :meth:`` method now accepts ``None`` for ``host``
and ``port`` arguments, using default values when ``None``. This
allows for calling run using configuration values, e.g.
``'MYHOST'), app.config.get('MYPORT'))``,
with proper behavior whether or not a config file is provided.
- The :meth:`flask.render_template` method now accepts a either an
iterable of template names or a single template name. Previously, it
only accepted a single template name. On an iterable, the first
template found is rendered.
- Added :meth:`flask.Flask.app_context` which works very similar to
the request context but only provides access to the current
application. This also adds support for URL generation without an
active request context.
- View functions can now return a tuple with the first instance being
an instance of :class:`flask.Response`. This allows for returning
``jsonify(error="error msg"), 400`` from a view function.
- :class:`~flask.Flask` and :class:`~flask.Blueprint` now provide a
:meth:`~flask.Flask.get_send_file_max_age` hook for subclasses to
override behavior of serving static files from Flask when using
:meth:`flask.Flask.send_static_file` (used for the default static
file handler) and :func:`~flask.helpers.send_file`. This hook is
provided a filename, which for example allows changing cache
controls by file extension. The default max-age for ``send_file``
and static files can be configured through a new
``SEND_FILE_MAX_AGE_DEFAULT`` configuration variable, which is used
in the default ``get_send_file_max_age`` implementation.
- Fixed an assumption in sessions implementation which could break
message flashing on sessions implementations which use external
- Changed the behavior of tuple return values from functions. They are
no longer arguments to the response object, they now have a defined
- Added :attr:`flask.Flask.request_globals_class` to allow a specific
class to be used on creation of the :data:`~flask.g` instance of
each request.
- Added ``required_methods`` attribute to view functions to force-add
methods on registration.
- Added :func:`flask.after_this_request`.
- Added :func:`flask.stream_with_context` and the ability to push
contexts multiple times without producing unexpected behavior.


Not secure

Released 2012-07-01

- Fixed an issue with the undocumented ``flask.session`` module to not
work properly on Python 2.5. It should not be used but did cause
some problems for package managers.


Not secure

Released 2011-09-29, codename Rakija

- Refactored session support into a session interface so that the
implementation of the sessions can be changed without having to
override the Flask class.
- Empty session cookies are now deleted properly automatically.
- View functions can now opt out of getting the automatic OPTIONS
- HTTP exceptions and Bad Request errors can now be trapped so that
they show up normally in the traceback.
- Flask in debug mode is now detecting some common problems and tries
to warn you about them.
- Flask in debug mode will now complain with an assertion error if a
view was attached after the first request was handled. This gives
earlier feedback when users forget to import view code ahead of
- Added the ability to register callbacks that are only triggered once
at the beginning of the first request.
- Malformed JSON data will now trigger a bad request HTTP exception
instead of a value error which usually would result in a 500
internal server error if not handled. This is a backwards
incompatible change.
- Applications now not only have a root path where the resources and
modules are located but also an instance path which is the
designated place to drop files that are modified at runtime (uploads
etc.). Also this is conceptually only instance depending and outside
version control so it's the perfect place to put configuration files
- Added the ``APPLICATION_ROOT`` configuration variable.
- Implemented :meth:`~flask.testing.TestClient.session_transaction` to
easily modify sessions from the test environment.
- Refactored test client internally. The ``APPLICATION_ROOT``
configuration variable as well as ``SERVER_NAME`` are now properly
used by the test client as defaults.
- Added :attr:`flask.views.View.decorators` to support simpler
decorating of pluggable (class-based) views.
- Fixed an issue where the test client if used with the "with"
statement did not trigger the execution of the teardown handlers.
- Added finer control over the session cookie parameters.
- HEAD requests to a method view now automatically dispatch to the
``get`` method if no handler was implemented.
- Implemented the virtual :mod:`flask.ext` package to import
extensions from.
- The context preservation on exceptions is now an integral component
of Flask itself and no longer of the test client. This cleaned up
some internal logic and lowers the odds of runaway request contexts
in unittests.
- Fixed the Jinja2 environment's ``list_templates`` method not
returning the correct names when blueprints or modules were


Not secure

Released 2011-07-06

- Fixed an issue with URL processors not properly working on


Not secure

Released 2011-06-29

- Added missing future import that broke 2.5 compatibility.
- Fixed an infinite redirect issue with blueprints.


Not secure

Released 2011-06-28, codename Grappa

- Added :meth:`~flask.Flask.make_default_options_response` which can
be used by subclasses to alter the default behavior for ``OPTIONS``
- Unbound locals now raise a proper :exc:`RuntimeError` instead of an
- Mimetype guessing and etag support based on file objects is now
deprecated for :func:`flask.send_file` because it was unreliable.
Pass filenames instead or attach your own etags and provide a proper
mimetype by hand.
- Static file handling for modules now requires the name of the static
folder to be supplied explicitly. The previous autodetection was not
reliable and caused issues on Google's App Engine. Until 1.0 the old
behavior will continue to work but issue dependency warnings.
- Fixed a problem for Flask to run on jython.
- Added a ``PROPAGATE_EXCEPTIONS`` configuration variable that can be
used to flip the setting of exception propagation which previously
was linked to ``DEBUG`` alone and is now linked to either ``DEBUG``
or ``TESTING``.
- Flask no longer internally depends on rules being added through the
``add_url_rule`` function and can now also accept regular werkzeug
rules added to the url map.
- Added an ``endpoint`` method to the flask application object which
allows one to register a callback to an arbitrary endpoint with a
- Use Last-Modified for static file sending instead of Date which was
incorrectly introduced in 0.6.
- Added ``create_jinja_loader`` to override the loader creation
- Implemented a silent flag for ``config.from_pyfile``.
- Added ``teardown_request`` decorator, for functions that should run
at the end of a request regardless of whether an exception occurred.
Also the behavior for ``after_request`` was changed. It's now no
longer executed when an exception is raised.
- Implemented :func:`flask.has_request_context`
- Deprecated ``init_jinja_globals``. Override the
:meth:`~flask.Flask.create_jinja_environment` method instead to
achieve the same functionality.
- Added :func:`flask.safe_join`
- The automatic JSON request data unpacking now looks at the charset
mimetype parameter.
- Don't modify the session on :func:`flask.get_flashed_messages` if
there are no messages in the session.
- ``before_request`` handlers are now able to abort requests with
- It is not possible to define user exception handlers. That way you
can provide custom error messages from a central hub for certain
errors that might occur during request processing (for instance
database connection errors, timeouts from remote resources etc.).
- Blueprints can provide blueprint specific error handlers.
- Implemented generic class-based views.


Not secure

Released 2010-12-31

- Fixed an issue where the default ``OPTIONS`` response was not
exposing all valid methods in the ``Allow`` header.
- Jinja2 template loading syntax now allows "./" in front of a
template load path. Previously this caused issues with module
- Fixed an issue where the subdomain setting for modules was ignored
for the static folder.
- Fixed a security problem that allowed clients to download arbitrary
files if the host server was a windows based operating system and
the client uses backslashes to escape the directory the files where
exposed from.


Not secure

Released 2010-07-27, codename Whisky

- After request functions are now called in reverse order of
- OPTIONS is now automatically implemented by Flask unless the
application explicitly adds 'OPTIONS' as method to the URL rule. In
this case no automatic OPTIONS handling kicks in.
- Static rules are now even in place if there is no static folder for
the module. This was implemented to aid GAE which will remove the
static folder if it's part of a mapping in the .yml file.
- The :attr:`~flask.Flask.config` is now available in the templates as
- Context processors will no longer override values passed directly to
the render function.
- Added the ability to limit the incoming request data with the new
``MAX_CONTENT_LENGTH`` configuration value.
- The endpoint for the :meth:`flask.Module.add_url_rule` method is now
optional to be consistent with the function of the same name on the
application object.
- Added a :func:`flask.make_response` function that simplifies
creating response object instances in views.
- Added signalling support based on blinker. This feature is currently
optional and supposed to be used by extensions and applications. If
you want to use it, make sure to have `blinker`_ installed.
- Refactored the way URL adapters are created. This process is now
fully customizable with the :meth:`~flask.Flask.create_url_adapter`
- Modules can now register for a subdomain instead of just an URL
prefix. This makes it possible to bind a whole module to a
configurable subdomain.

.. _blinker:


Not secure

Released 2010-07-15

- Fixed another issue with loading templates from directories when
modules were used.


Not secure

Released 2010-07-06

- Fixes an issue with template loading from directories when modules
where used.


Not secure

Released 2010-07-06, codename Calvados

- Fixed a bug with subdomains that was caused by the inability to
specify the server name. The server name can now be set with the
``SERVER_NAME`` config key. This key is now also used to set the
session cookie cross-subdomain wide.
- Autoescaping is no longer active for all templates. Instead it is
only active for ``.html``, ``.htm``, ``.xml`` and ``.xhtml``. Inside
templates this behavior can be changed with the ``autoescape`` tag.
- Refactored Flask internally. It now consists of more than a single
- :func:`flask.send_file` now emits etags and has the ability to do
conditional responses builtin.
- (temporarily) dropped support for zipped applications. This was a
rarely used feature and led to some confusing behavior.
- Added support for per-package template and static-file directories.
- Removed support for ``create_jinja_loader`` which is no longer used
in 0.5 due to the improved module support.
- Added a helper function to expose files from any directory.


Not secure

Released 2010-06-18, codename Rakia

- Added the ability to register application wide error handlers from
- :meth:`~flask.Flask.after_request` handlers are now also invoked if
the request dies with an exception and an error handling page kicks
- Test client has not the ability to preserve the request context for
a little longer. This can also be used to trigger custom requests
that do not pop the request stack for testing.
- Because the Python standard library caches loggers, the name of the
logger is configurable now to better support unittests.
- Added ``TESTING`` switch that can activate unittesting helpers.
- The logger switches to ``DEBUG`` mode now if debug is enabled.


Not secure

Released 2010-05-28

- Fixed a error reporting bug with :meth:`flask.Config.from_envvar`
- Removed some unused code from flask
- Release does no longer include development leftover files (.git
folder for themes, built documentation in zip and pdf file and some
.pyc files)


Not secure

Released 2010-05-28, codename Schnaps

- Added support for categories for flashed messages.
- The application now configures a :class:`logging.Handler` and will
log request handling exceptions to that logger when not in debug
mode. This makes it possible to receive mails on server errors for
- Added support for context binding that does not require the use of
the with statement for playing in the console.
- The request context is now available within the with statement
making it possible to further push the request context or pop it.
- Added support for configurations.


Not secure

Released 2010-05-12, codename J?germeister

- Various bugfixes
- Integrated JSON support
- Added :func:`~flask.get_template_attribute` helper function.
- :meth:`~flask.Flask.add_url_rule` can now also register a view
- Refactored internal request dispatching.
- Server listens on by default now to fix issues with
- Added external URL support.
- Added support for :func:`~flask.send_file`
- Module support and internal request handling refactoring to better
support pluggable applications.
- Sessions can be set to be permanent now on a per-session basis.
- Better error reporting on missing secret keys.
- Added support for Google Appengine.


Not secure

Released 2010-04-16

- First public preview release.