Filed by: chorotan [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=410318916&repo=mozilla-central
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/CecEvfHQSzyiiL_KAe_KRw/runs/0/artifacts/public/logs/live_backing.log

[task 2023-03-27T10:14:53.197Z] 10:14:53     INFO - TEST-PASS | leakcheck | tab no leaks detected!
[task 2023-03-27T10:14:53.198Z] 10:14:53     INFO - runtests.py | Running tests: end.
[task 2023-03-27T10:14:53.216Z] 10:14:53     INFO -  Failed to unload module: Module b'46\n' not loaded
[task 2023-03-27T10:14:53.224Z] 10:14:53     INFO -  Failed to unload module: Module b'47\n' not loaded
[task 2023-03-27T10:14:53.230Z] 10:14:53     INFO -  Failed to unload module: Module b'48\n' not loaded
[task 2023-03-27T10:14:53.238Z] 10:14:53     INFO -  Failed to unload module: Module b'49\n' not loaded
[task 2023-03-27T10:14:53.241Z] 10:14:53     INFO - Buffered messages finished
[task 2023-03-27T10:14:53.242Z] 10:14:53     INFO - Running manifest: toolkit/components/extensions/test/mochitest/mochitest.ini:toolkit/components/extensions/test/mochitest/mochitest-common.ini
[task 2023-03-27T10:14:53.242Z] 10:14:53     INFO - The following extra prefs will be set:
[task 2023-03-27T10:14:53.243Z] 10:14:53     INFO -   extensions.webextensions.remote=false
[task 2023-03-27T10:14:53.243Z] 10:14:53     INFO -   javascript.options.asyncstack_capture_debuggee_only=false
[task 2023-03-27T10:14:53.244Z] 10:14:53     INFO -   security.mixed_content.upgrade_display_content=false
[task 2023-03-27T10:14:53.244Z] 10:14:53     INFO -   browser.chrome.guess_favicon=true
[task 2023-03-27T10:14:53.277Z] 10:14:53     INFO -  Setting pipeline to PAUSED ...
[task 2023-03-27T10:14:53.278Z] 10:14:53     INFO -  Pipeline is PREROLLING ...
[task 2023-03-27T10:14:53.287Z] 10:14:53     INFO - use doh server at port: 48012
[task 2023-03-27T10:14:53.287Z] 10:14:53     INFO - use http3 server at port: 34575
[task 2023-03-27T10:14:53.293Z] 10:14:53     INFO -  Pipeline is PREROLLED ...
[task 2023-03-27T10:14:53.293Z] 10:14:53     INFO -  Setting pipeline to PLAYING ...
[task 2023-03-27T10:14:53.294Z] 10:14:53     INFO -  New clock: GstSystemClock
[task 2023-03-27T10:14:53.326Z] 10:14:53     INFO -  Got EOS from element "pipeline0".
[task 2023-03-27T10:14:53.327Z] 10:14:53     INFO -  Execution ended after 0:00:00.033463686
[task 2023-03-27T10:14:53.327Z] 10:14:53     INFO -  Setting pipeline to PAUSED ...
[task 2023-03-27T10:14:53.327Z] 10:14:53     INFO -  Setting pipeline to READY ...
[task 2023-03-27T10:14:53.328Z] 10:14:53     INFO -  (gst-launch-1.0:9749): GStreamer-CRITICAL **: 10:14:53.323: gst_object_unref: assertion '((GObject *) object)->ref_count > 0' failed
[task 2023-03-27T10:14:53.328Z] 10:14:53     INFO -  Setting pipeline to NULL ...
[task 2023-03-27T10:14:53.328Z] 10:14:53     INFO -  Freeing pipeline ...
[task 2023-03-27T10:14:53.501Z] 10:14:53     INFO - PID 9774 | pk12util: PKCS12 IMPORT SUCCESSFUL
[task 2023-03-27T10:14:53.542Z] 10:14:53     INFO - MochitestServer : launching ['/builds/worker/workspace/build/tests/bin/xpcshell', '-g', '/builds/worker/workspace/build/application/firefox', '-f', '/builds/worker/workspace/build/tests/bin/components/httpd.js', '-e', "const _PROFILE_PATH = '/tmp/tmppf98uibo.mozrunner'; const _SERVER_PORT = '8888'; const _SERVER_ADDR = '127.0.0.1'; const _TEST_PREFIX = undefined; const _DISPLAY_RESULTS = false;", '-f', '/builds/worker/workspace/build/tests/mochitest/server.js']
[task 2023-03-27T10:14:53.543Z] 10:14:53     INFO - runtests.py | Server pid: 9777
[task 2023-03-27T10:14:53.563Z] 10:14:53     INFO - runtests.py | Websocket server pid: 9780
[task 2023-03-27T10:14:53.603Z] 10:14:53     INFO - runtests.py | SSL tunnel pid: 9784
[task 2023-03-27T10:14:53.713Z] 10:14:53     INFO -  Couldn't convert chrome URL: chrome://branding/locale/brand.properties
[task 2023-03-27T10:14:53.715Z] 10:14:53     INFO -  [Parent 9777, Main Thread] WARNING: Could not get the program name for a cubeb stream.: 'NS_SUCCEEDED(rv)', file /builds/worker/checkouts/gecko/dom/media/CubebUtils.cpp:430
[task 2023-03-27T10:14:53.756Z] 10:14:53     INFO - use http3 server: 1
[task 2023-03-27T10:14:53.756Z] 10:14:53     INFO - mozserve | Found Http3Server path: /builds/worker/workspace/build/tests/bin/http3server
[task 2023-03-27T10:14:53.757Z] 10:14:53     INFO - mozserve | cert db path: /tmp/tmppf98uibo.mozrunner
[task 2023-03-27T10:14:53.778Z] 10:14:53     INFO - mozserve | http3 server msg: 
[task 2023-03-27T10:14:53.778Z] 10:14:53     INFO -  Traceback (most recent call last):
[task 2023-03-27T10:14:53.779Z] 10:14:53     INFO -    File "/builds/worker/workspace/build/tests/mochitest/runtests.py", line 3574, in doTests
[task 2023-03-27T10:14:53.780Z] 10:14:53     INFO -      self.startServers(options, debuggerInfo)
[task 2023-03-27T10:14:53.780Z] 10:14:53     INFO -    File "/builds/worker/workspace/build/tests/mochitest/runtests.py", line 1471, in startServers
[task 2023-03-27T10:14:53.785Z] 10:14:53     INFO -      self.startHttp3Server(options)
[task 2023-03-27T10:14:53.785Z] 10:14:53     INFO -    File "/builds/worker/workspace/build/tests/mochitest/runtests.py", line 1401, in startHttp3Server
[task 2023-03-27T10:14:53.786Z] 10:14:53     INFO -      if int(port) != options.http3ServerPort:
[task 2023-03-27T10:14:53.786Z] 10:14:53     INFO -  TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'
[task 2023-03-27T10:14:53.787Z] 10:14:53    ERROR - Automation Error: Received unexpected exception while running application
[task 2023-03-27T10:14:53.787Z] 10:14:53    ERROR - 

:kershaw - can you have a look at this?

Somehow the UDP port can be used by http3server.

[task 2023-03-27T10:14:53.872Z] 10:14:53     INFO - Http3 server http3Server already dead 1
[task 2023-03-27T10:14:53.873Z] 10:14:53     INFO - Process stderr
[task 2023-03-27T10:14:53.873Z] 10:14:53     INFO - Unable to bind UDP socket: Address already in use (os error 98)

I'll try to find a better way to find a free port.

https://hg.mozilla.org/mozilla-central/rev/9d0febec22e4

This is still happening, the patch did not fix the issue: https://treeherder.mozilla.org/jobs?repo=autoland&revision=8ff185f84377808c981e71eee8f5ceeebde7e7f5&selectedTaskRun=TdtCJA45RQekXmB4w7PvxQ.0&searchStr=Linux%2C18.04%2Cx64%2CWebRender%2Cdebug%2CMochitests%2Cwith%2CHttp%2F3%2Cserver%2Ctest-linux1804-64-qr%2Fdebug-mochitest-devtools-chrome-http3%2Cdt11&group_state=expanded