CI run against Twisted trunk is failing

[github-actions]

See https://github.com/element-hq/synapse/actions/runs/12368825338

[anoadragon453]

The errors:

mypy:

synapse/http/proxy.py:92: error: "Headers" has no attribute "_canonicalNameCaps"  [attr-defined]

unit tests:

Error: 
Traceback (most recent call last):
  File "/home/runner/work/synapse/synapse/tests/test_server.py", line 419, in test_redirect_exception_with_cookie
    location_headers = [v for k, v in headers if k == b"Location"]
builtins.TypeError: 'Headers' object is not iterable

tests.test_server.WrapHtmlRequestHandlerTests.test_redirect_exception_with_cookie
===============================================================================
Error: 
Traceback (most recent call last):
  File "/home/runner/work/synapse/synapse/tests/test_server.py", line 396, in test_redirect_exception
    location_headers = [v for k, v in headers if k == b"Location"]
builtins.TypeError: 'Headers' object is not iterable

tests.test_server.WrapHtmlRequestHandlerTests.test_redirect_exception

[arkamar]

I have bisected the twisted. The "Headers" has no attribute "_canonicalNameCaps" issue was introduced in PR twisted/twisted#12117 and the builtins.TypeError: 'Headers' object is not iterable issue was introduced in PR twisted/twisted#12157

[mgorny]

This was now released as 24.10.0rc1, and therefore will hit a stable release real soon.

[tgurr]

Just hit the error with the now released version 24.10.0 https://pypi.org/project/Twisted/24.10.0/ that synapse won't work anymore after upgrading to that version.

[gramakri]

Related: #17882

[anoadragon453]

Thanks all. The team is aware and actively working on a fix for the next Synapse release 🙂

[arkamar]

For the record, one test fails in 1.119.0 with Twisted 24.10.0

===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/usr/lib/python3.13/site-packages/twisted/logger/_observer.py", line 81, in __call__
    observer(event)
  File "/usr/lib/python3.13/site-packages/twisted/logger/_legacy.py", line 90, in __call__
    self.legacyObserver(event)
  File "/usr/lib/python3.13/site-packages/twisted/trial/_dist/workertrial.py", line 44, in emit
    self.protocol.callRemote(managercommands.TestWrite, out=text)
  File "/usr/lib/python3.13/site-packages/twisted/protocols/amp.py", line 951, in callRemote
    return co._doCommand(self)
  File "/usr/lib/python3.13/site-packages/twisted/protocols/amp.py", line 1973, in _doCommand
    d = proto._sendBoxCommand(
  File "/usr/lib/python3.13/site-packages/twisted/protocols/amp.py", line 884, in _sendBoxCommand
    box._sendTo(self.boxSender)
  File "/usr/lib/python3.13/site-packages/twisted/protocols/amp.py", line 713, in _sendTo
    proto.sendBox(self)
  File "/usr/lib/python3.13/site-packages/twisted/protocols/amp.py", line 2358, in sendBox
    self.transport.write(box.serialize())
  File "/usr/lib/python3.13/site-packages/twisted/protocols/amp.py", line 692, in serialize
    raise TooLong(False, True, v, k)
twisted.protocols.amp.TooLong:

tests.storage.databases.main.test_events_worker.DatabaseOutageTestCase.test_recovery
-------------------------------------------------------------------------------
Ran 3885 tests in 146.810s

FAILED (skips=294, errors=1, successes=3590)

The same error is detected here https://github.com/element-hq/synapse/actions/runs/11801798008/job/32876109329?pr=17878

[anoadragon453]

Based on local testing, this should have been fixed by #17998

➜ pip install -U git+https://github.com/twisted/twisted.git#trunk
[...snip...]
      Successfully uninstalled Twisted-24.7.0
Successfully installed Twisted-24.11.0.post0 automat-24.8.1

➜ mypy
Success: no issues found in 916 source files