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Release Notes

0.38.0 (October 18, 2025)

Added

  • Support Python 3.14 (#2723)

0.37.0 (September 23, 2025)

Added

  • Add --timeout-worker-healthcheck option (#2711)
  • Add os.PathLike[str] type to ssl_ca_certs (#2676)

0.36.1 (September 23, 2025)

Fixed

  • Raise an exception when calling removed Config.setup_event_loop() (#2709)

0.36.0 (September 20, 2025)

Added

  • Support custom IOLOOPs (#2435)
  • Allow to provide importable string in --http, --ws and --loop (#2658)

0.35.0 (June 28, 2025)

Added

  • Add WebSocketsSansIOProtocol (#2540)

Changed

  • Refine help message for option --proxy-headers (#2653)

0.34.3 (June 1, 2025)

Fixed

  • Don't include cwd() when non-empty --reload-dirs is passed (#2598)
  • Apply get_client_addr formatting to WebSocket logging (#2636)

0.34.2 (April 19, 2025)

Fixed

  • Flush stdout buffer on Windows to trigger reload (#2604)

0.34.1 (April 13, 2025)

Deprecated

  • Deprecate ServerState in the main module (#2581)

0.34.0 (December 15, 2024)

Added

  • Add content-length to 500 response in wsproto implementation (#2542)

Removed

  • Drop support for Python 3.8 (#2543)

0.33.0 (December 14, 2024)

Removed

  • Remove WatchGod support for --reload (#2536)

0.32.1 (November 20, 2024)

Fixed

  • Drop ASGI spec version to 2.3 on HTTP scope (#2513)
  • Enable httptools lenient data on httptools >= 0.6.3 (#2488)

0.32.0 (October 15, 2024)

Added

  • Officially support Python 3.13 (#2482)
  • Warn when max_request_limit is exceeded (#2430)

0.31.1 (October 9, 2024)

Fixed

  • Support WebSockets 0.13.1 (#2471)
  • Restore support for [*] in trusted hosts (#2480)
  • Add PathLike[str] type hint for ssl_keyfile (#2481)

0.31.0 (September 27, 2024)

Added

Improve ProxyHeadersMiddleware (#2468) and (#2231):

  • Fix the host for requests from clients running on the proxy server itself.
  • Fallback to host that was already set for empty x-forwarded-for headers.
  • Also allow to specify IP Networks as trusted hosts. This greatly simplifies deployments on docker swarm/kubernetes, where the reverse proxy might have a dynamic IP.
    • This includes support for IPv6 Address/Networks.

0.30.6 (August 13, 2024)

Fixed

  • Don't warn when upgrade is not WebSocket and depedencies are installed (#2360)

0.30.5 (August 2, 2024)

Fixed

  • Don't close connection before receiving body on H11 (#2408)

0.30.4 (July 31, 2024)

Fixed

  • Close connection when h11 sets client state to MUST_CLOSE (#2375)

0.30.3 (July 20, 2024)

Fixed

  • Suppress KeyboardInterrupt from CLI and programmatic usage (#2384)
  • ClientDisconnect inherits from OSError instead of IOError (#2393)

0.30.2 (July 20, 2024)

Added

Fixed

  • Iterate subprocesses in-place on the process manager (#2373)

0.30.1 (June 2, 2024)

Fixed

  • Allow horizontal tabs \t in response header values (#2345)

0.30.0 (May 28, 2024)

Added

  • New multiprocess manager (#2183)
  • Allow ConfigParser or a io.IO[Any] on log_config (#1976)

Fixed

  • Suppress side-effects of signal propagation (#2317)
  • Send content-length header on 5xx (#2304)

Deprecated

  • Deprecate the uvicorn.workers module (#2302)

0.29.0 (March 19, 2024)

Added

  • Cooperative signal handling (#1600)

0.28.1 (March 19, 2024)

Fixed

  • Revert raise ClientDisconnected on HTTP (#2276)

0.28.0 (March 9, 2024)

Added

  • Raise ClientDisconnected on send() when client disconnected (#2220)

Fixed

  • Except AttributeError on sys.stdin.fileno() for Windows IIS10 (#1947)
  • Use X-Forwarded-Proto for WebSockets scheme when the proxy provides it (#2258)

0.27.1 (February 10, 2024)

  • Fix spurious LocalProtocolError errors when processing pipelined requests (#2243)

0.27.0.post1 (January 29, 2024)

Fixed

  • Fix nav overrides for newer version of Mkdocs Material (#2233)

0.27.0 (January 22, 2024)

Added

  • Raise ClientDisconnect(IOError) on send() when client disconnected (#2218)
  • Bump ASGI WebSocket spec version to 2.4 (#2221)

0.26.0 (January 16, 2024)

Changed

  • Update --root-path to include the root path prefix in the full ASGI path as per the ASGI spec (#2213)
  • Use __future__.annotations on some internal modules (#2199)

0.25.0 (December 17, 2023)

Added

  • Support the WebSocket Denial Response ASGI extension (#1916)

Fixed

  • Allow explicit hidden file paths on --reload-include (#2176)
  • Properly annotate uvicorn.run() (#2158)

0.24.0.post1 (November 6, 2023)

Fixed

  • Revert mkdocs-material from 9.1.21 to 9.2.6 (#2148)

0.24.0 (November 4, 2023)

Added

  • Support Python 3.12 (#2145)
  • Allow setting app via environment variable UVICORN_APP (#2106)

0.23.2 (July 31, 2023)

Fixed

  • Maintain the same behavior of websockets from 10.4 on 11.0 (#2061)

0.23.1 (July 18, 2023)

Fixed

  • Add typing_extensions for Python 3.10 and lower (#2053)

0.23.0 (July 10, 2023)

Added

  • Add --ws-max-queue parameter WebSockets (#2033)

Removed

  • Drop support for Python 3.7 (#1996)
  • Remove asgiref as typing dependency (#1999)

Fixed

  • Set scope["scheme"] to ws or wss instead of http or https on ProxyHeadersMiddleware for WebSockets (#2043)

Changed

  • Raise ImportError on circular import (#2040)
  • Use logger.getEffectiveLevel() instead of logger.level to check if log level is TRACE (#1966)

0.22.0 (April 28, 2023)

Added

  • Add --timeout-graceful-shutdown parameter (#1950)
  • Handle SIGBREAK on Windows (#1909)

Fixed

  • Shutdown event is now being triggered on Windows when using hot reload (#1584)
  • --reload-delay is effectively used on the watchfiles reloader (#1930)

0.21.1 (March 16, 2023)

Fixed

  • Reset lifespan state on each request (#1903)

0.21.0 (March 9, 2023)

Added

  • Introduce lifespan state (#1818)
  • Allow headers to be sent as iterables on H11 implementation (#1782)
  • Improve discoverability when --port=0 is used (#1890)

Changed

  • Avoid importing h11 and pyyaml when not needed to improve import time (#1846)
  • Replace current native WSGIMiddleware implementation by a2wsgi (#1825)
  • Change default --app-dir from "." (dot) to "" (empty string) (#1835)

Fixed

  • Send code 1012 on shutdown for WebSockets (#1816)
  • Use surrogateescape to encode headers on websockets implementation (#1005)
  • Fix warning message on reload failure (#1784)

0.20.0 (November 20, 2022)

Added

  • Check if handshake is completed before sending frame on wsproto shutdown (#1737)
  • Add default headers to WebSockets implementations (#1606 & #1747)
  • Warn user when reload and workers flag are used together (#1731)

Fixed

  • Use correct WebSocket error codes on close (#1753)
  • Send disconnect event on connection lost for wsproto (#996)
  • Add SIGQUIT handler to UvicornWorker (#1710)
  • Fix crash on exist with "--uds" if socket doesn't exist (#1725)
  • Annotate CONFIG_KWARGS in UvicornWorker class (#1746)

Removed

  • Remove conditional on RemoteProtocolError.event_hint on wsproto (#1486)
  • Remove unused handle_no_connect on wsproto implementation (#1759)

0.19.0 (October 19, 2022)

Added

  • Support Python 3.11 (#1652)
  • Bump minimal httptools version to 0.5.0 (#1645)
  • Ignore HTTP/2 upgrade and optionally ignore WebSocket upgrade (#1661)
  • Add py.typed to comply with PEP 561 (#1687)

Fixed

  • Set propagate to False on "uvicorn" logger (#1288)
  • USR1 signal is now handled correctly on UvicornWorker. (#1565)
  • Use path with query string on WebSockets logs (#1385)
  • Fix behavior on which "Date" headers were not updated on the same connection (#1706)

Removed

  • Remove the --debug flag (#1640)
  • Remove the DebugMiddleware (#1697)

0.18.3 (August 24, 2022)

Fixed

  • Remove cyclic references on HTTP implementations. (#1604)

Changed

  • reload_delay default changed from None to 0.25 on uvicorn.run() and Config. None is not an acceptable value anymore. (#1545)

0.18.2 (June 27, 2022)

Fixed

  • Add default log_config on uvicorn.run() (#1541)
  • Revert logging file name modification (#1543)

0.18.1 (June 23, 2022)

Fixed

  • Use DEFAULT_MAX_INCOMPLETE_EVENT_SIZE as default to h11_max_incomplete_event_size on the CLI (#1534)

0.18.0 (June 23, 2022)

Added

  • The reload flag prioritizes watchfiles instead of the deprecated watchgod (#1437)
  • Annotate uvicorn.run() function (#1423)
  • Allow configuring max_incomplete_event_size for h11 implementation (#1514)

Removed

  • Remove asgiref dependency (#1532)

Fixed

  • Turn raw_path into bytes on both websockets implementations (#1487)
  • Revert log exception traceback in case of invalid HTTP request (#1518)
  • Set asyncio.WindowsSelectorEventLoopPolicy() when using multiple workers to avoid "WinError 87" (#1454)

0.17.6 (March 11, 2022)

Changed

  • Change httptools range to >=0.4.0 (#1400)

0.17.5 (February 16, 2022)

Fixed

  • Fix case where url is fragmented in httptools protocol (#1263)
  • Fix WSGI middleware not to explode quadratically in the case of a larger body (#1329)

Changed

  • Send HTTP 400 response for invalid request (#1352)

0.17.4 (February 4, 2022)

Fixed

  • Replace create_server by create_unix_server (#1362)

0.17.3 (February 3, 2022)

Fixed

  • Drop wsproto version checking. (#1359)

0.17.2 (February 3, 2022)

Fixed

  • Revert #1332. While trying to solve the memory leak, it introduced an issue (#1345) when the server receives big chunks of data using the httptools implementation. (#1354)
  • Revert stream interface changes. This was introduced on 0.14.0, and caused an issue (#1226), which caused a memory leak when sending TCP pings. (#1355)
  • Fix wsproto version check expression (#1342)

0.17.1 (January 28, 2022)

Fixed

  • Move all data handling logic to protocol and ensure connection is closed. (#1332)
  • Change spec_version field from "2.1" to "2.3", as Uvicorn is compliant with that version of the ASGI specifications. (#1337)

0.17.0.post1 (January 24, 2022)

Fixed

  • Add the python_requires version specifier (#1328)

0.17.0 (January 14, 2022)

Added

  • Allow configurable websocket per-message-deflate setting (#1300)
  • Support extra_headers for WS accept message (#1293)
  • Add missing http version on websockets scope (#1309)

Fixed/Removed

  • Drop Python 3.6 support (#1261)
  • Fix reload process behavior when exception is raised (#1313)
  • Remove root_path from logs (#1294)

0.16.0 (December 8, 2021)

Added

  • Enable read of uvicorn settings from environment variables (#1279)
  • Bump websockets to 10.0. (#1180)
  • Ensure non-zero exit code when startup fails (#1278)
  • Increase httptools version range from "==0.2.*" to ">=0.2.0,<0.4.0". (#1243)
  • Override default asyncio event loop with reload only on Windows (#1257)
  • Replace HttpToolsProtocol.pipeline type from list to deque. (#1213)
  • Replace WSGIResponder.send_queue type from list to deque. (#1214)

Fixed

  • Main process exit after startup failure on reloader classes (#1177)
  • Fix the need of httptools on minimal installation (#1135)
  • Fix ping parameters annotation in Config class (#1127)

0.15.0 (August 13, 2021)

Added

  • Change reload to be configurable with glob patterns. Currently only .py files are watched, which is different from the previous default behavior. (#820)
  • Add Python 3.10-rc.1 support. Now the server uses asyncio.run which will: start a fresh asyncio event loop, on shutdown cancel any background tasks rather than aborting them, aexit any remaining async generators, and shutdown the default ThreadPoolExecutor. (#1070)
  • Exit with status 3 when worker starts failed (#1077)
  • Add option to set websocket ping interval and timeout (#1048)
  • Adapt bind_socket to make it usable with multiple processes (#1009)
  • Add existence check to the reload directory(ies) (#1089)
  • Add missing trace log for websocket protocols (#1083)
  • Support disabling default Server and Date headers (#818)

Changed

  • Add PEP440 compliant version of click (#1099)
  • Bump asgiref to 3.4.0 (#1100)

Fixed

  • When receiving a SIGTERM supervisors now terminate their processes before joining them (#1069)
  • Fix httptools range to >=0.4.0 (#1400)

0.14.0 (June 1, 2021)

Added

  • Defaults ws max_size on server to 16MB (#995)
  • Improve user feedback if no ws library installed (#926 and #1023)
  • Support 'reason' field in 'websocket.close' messages (#957)
  • Implemented lifespan.shutdown.failed (#755)

Changed

  • Upgraded websockets requirements (#1065)
  • Switch to asyncio streams API (#869)
  • Update httptools from 0.1.* to 0.2.* (#1024)
  • Allow Click 8.0, refs #1016 (#1042)
  • Add search for a trusted host in ProxyHeadersMiddleware (#591)
  • Up wsproto to 1.0.0 (#892)

Fixed

  • Force reload_dirs to be a list (#978)
  • Fix gunicorn worker not running if extras not installed (#901)
  • Fix socket port 0 (#975)
  • Prevent garbage collection of main lifespan task (#972)

0.13.4 (February 20, 2021)

Fixed

  • Fixed wsgi middleware PATH_INFO encoding (#962)
  • Fixed uvloop dependency (#952) then (#959)
  • Relax watchgod up bound (#946)
  • Return 'connection: close' header in response (#721)

Added

  • Docs: Nginx + websockets (#948)
  • Document the default value of 1 for workers (#940) (#943)
  • Enabled permessage-deflate extension in websockets (#764)

0.13.3 (December 29, 2020)

Fixed

  • Prevent swallowing of return codes from subprocess when running with Gunicorn by properly resetting signals. (#895)
  • Tweak detection of app factories to be more robust. A warning is now logged when passing a factory without the --factory flag. (#914)
  • Properly clean tasks when handshake is aborted when running with --ws websockets. (#921)

0.13.2 (December 12, 2020)

Fixed

  • Log full exception traceback in case of invalid HTTP request. (#886 and #888)

0.13.1 (December 12, 2020)

Fixed

  • Prevent exceptions when the ASGI application rejects a connection during the WebSocket handshake, when running on both --ws wsproto or --ws websockets. (#704 and #881)
  • Ensure connection scope doesn't leak in logs when using JSON log formatters. (#859 and #884)

0.13.0 (December 8, 2020)

Added

  • Add --factory flag to support factory-style application imports. (#875)
  • Skip installation of signal handlers when not in the main thread. Allows using Server in multithreaded contexts without having to override .install_signal_handlers(). (#871)

0.12.3 (November 21, 2020)

Fixed

  • Fix race condition that leads Quart to hang with uvicorn (#848)
  • Use latin1 when decoding X-Forwarded-* headers (#701)
  • Rework IPv6 support (#837)
  • Cancel old keepalive-trigger before setting new one. (#832)

0.12.2 (October 19, 2020)

Added

  • Adding ability to decrypt ssl key file (#808)
  • Support .yml log config files (#799)
  • Added python 3.9 support (#804)

Fixed

  • Fixes watchgod with common prefixes (#817)
  • Fix reload with ipv6 host (#803)
  • Added cli support for headers containing colon (#813)
  • Sharing socket across workers on windows (#802)
  • Note the need to configure trusted "ips" when using unix sockets (#796)

0.12.1 (September 30, 2020)

Changed

  • Pinning h11 and python-dotenv to min versions (#789)
  • Get docs/index.md in sync with README.md (#784)

Fixed

  • Improve changelog by pointing out breaking changes (#792)

0.12.0 (September 28, 2020)

Added

  • Make reload delay configurable (#774)
  • Upgrade maximum h11 dependency version to 0.10 (#772)
  • Allow .json or .yaml --log-config files (#665)
  • Add ASGI dict to the lifespan scope (#754)
  • Upgrade wsproto to 0.15.0 (#750)
  • Use optional package installs (#666)

Changed

  • Don't set log level for root logger (#767) 8/28/20 df81b168
  • Uvicorn no longer ships extra dependencies uvloop, websockets and httptools as default. To install these dependencies use uvicorn[standard].

Fixed

  • Revert "Improve shutdown robustness when using --reload or multiprocessing (#620)" (#756)
  • Fix terminate error in windows (#744)
  • Fix bug where --log-config disables uvicorn loggers (#512)

0.11.8 (July 30, 2020)

  • Fix a regression that caused Uvicorn to crash when using --interface=wsgi. (#730)
  • Fix a regression that caused Uvicorn to crash when using unix domain sockets. (#729)

0.11.7 (July 28, 2020)

  • SECURITY FIX: Prevent sending invalid HTTP header names and values. (#725)
  • SECURITY FIX: Ensure path value is escaped before logging to the console. (#724)
  • Fix --proxy-headers client IP and host when using a Unix socket. (#636)

0.11.6 (July 17, 2020)

  • Fix overriding the root logger.

0.11.5 (April 29, 2020)

  • Revert "Watch all files, not just .py" due to unexpected side effects.
  • Revert "Pass through gunicorn timeout config." due to unexpected side effects.

0.11.4 (April 28, 2020)

  • Use watchgod, if installed, for watching code changes.
  • Watch all files, not just .py.
  • Pass through gunicorn timeout config.

0.11.3 (February 17, 2020)

  • Update dependencies.

0.11.2 (January 20, 2020)

  • Don't open socket until after application startup.
  • Support --backlog.

0.11.1 (December 20, 2019)

  • Use a more liberal h11 dependency. Either 0.8.* or `0.9.*``.

0.11.0 (December 20, 2019)

  • Fix reload/multiprocessing on Windows with Python 3.8.
  • Drop IOCP support. (Required for fix above.)
  • Add uvicorn --version flag.
  • Add --use-colors and --no-use-colors flags.
  • Display port correctly, when auto port selection isused with --port=0.

0.10.8 (November 12, 2019)

  • Fix reload/multiprocessing error.

0.10.7 (November 12, 2019)

  • Use resource_sharer.DupSocket to resolve socket sharing on Windows.

0.10.6 (November 12, 2019)

  • Exit if workers or reload are use without an app import string style.
  • Reorganise supervisor processes to properly hand over sockets on windows.

0.10.5 (November 12, 2019)

  • Update uvloop dependency to 0.14+

0.10.4 (November 9, 2019)

  • Error clearly when workers=<NUM> is used with app instance, instead of an app import string.
  • Switch --reload-dir to current working directory by default.

0.10.3 (November 1, 2019)

  • Add `--log-level trace

0.10.2 (October 31, 2019)

  • Enable --proxy-headers by default.

0.10.1 (October 31, 2019)

  • Resolve issues with logging when using --reload or --workers.
  • Setup up root logger to capture output for all logger instances, not just uvicorn.error and uvicorn.access.

0.10.0 (October 29, 2019)

  • Support for Python 3.8
  • Separated out uvicorn.error and uvicorn.access logs.
  • Coloured log output when connected to a terminal.
  • Dropped logger= config setting.
  • Added --log-config [FILE] and log_config=[str|dict]. May either be a Python logging config dictionary or the file name of a logging configuration.
  • Added --forwarded_allow_ips and forwarded_allow_ips. Defaults to the value of the $FORWARDED_ALLOW_IPS environment variable or "127.0.0.1". The --proxy-headers flag now defaults to True, but only trusted IPs are used to populate forwarding info.
  • The --workers setting now defaults to the value of the $WEB_CONCURRENCY environment variable.
  • Added support for --env-file. Requires python-dotenv.