Python 3.14: TypeError: cannot pickle 'weakref.ReferenceType' object

[The-Compiler]

After upgrading my Archlinux system to Python 3.13, when launching keepmenu and entering my password, I get:

Traceback (most recent call last):
  File "/usr/bin/keepmenu", line 8, in <module>
    sys.exit(main())
             ~~~~^^
  File "/usr/lib/python3.14/site-packages/keepmenu/__main__.py", line 214, in main
    run(**args)
    ~~~^^^^^^^^
  File "/usr/lib/python3.14/site-packages/keepmenu/__main__.py", line 144, in run
    dmenu.start()
    ~~~~~~~~~~~^^
  File "/usr/lib/python3.14/multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
                  ~~~~~~~~~~~^^^^^^
  File "/usr/lib/python3.14/multiprocessing/context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/usr/lib/python3.14/multiprocessing/context.py", line 300, in _Popen
    return Popen(process_obj)
  File "/usr/lib/python3.14/multiprocessing/popen_forkserver.py", line 35, in __init__
    super().__init__(process_obj)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/usr/lib/python3.14/multiprocessing/popen_fork.py", line 20, in __init__
    self._launch(process_obj)
    ~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/usr/lib/python3.14/multiprocessing/popen_forkserver.py", line 47, in _launch
    reduction.dump(process_obj, buf)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.14/multiprocessing/reduction.py", line 60, in dump
    ForkingPickler(file, protocol).dump(obj)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^
TypeError: cannot pickle 'weakref.ReferenceType' object
when serializing dict item '_weakref'
when serializing multiprocessing.util.Finalize state
when serializing multiprocessing.util.Finalize object
when serializing dict item 'finalizer'
when serializing multiprocessing.popen_forkserver.Popen state
when serializing multiprocessing.popen_forkserver.Popen object
when serializing dict item '_popen'
when serializing keepmenu.__main__.Server state
when serializing keepmenu.__main__.Server object
when serializing dict item 'server'
when serializing keepmenu.keepmenu.DmenuRunner state
when serializing keepmenu.keepmenu.DmenuRunner object
Traceback (most recent call last):
  File "/usr/lib/python3.14/multiprocessing/forkserver.py", line 340, in main
    code = _serve_one(child_r, fds,
                      unused_fds,
                      old_handlers)
  File "/usr/lib/python3.14/multiprocessing/forkserver.py", line 380, in _serve_one
    code = spawn._main(child_r, parent_sentinel)
  File "/usr/lib/python3.14/multiprocessing/spawn.py", line 132, in _main
    self = reduction.pickle.load(from_parent)
  File "/usr/lib/python3.14/multiprocessing/synchronize.py", line 117, in __setstate__
    self._semlock = _multiprocessing.SemLock._rebuild(*state)
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory
Process Server-1:
Traceback (most recent call last):
  File "/usr/lib/python3.14/multiprocessing/process.py", line 320, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/usr/lib/python3.14/site-packages/keepmenu/__main__.py", line 105, in run
    _ = self.server()
  File "/usr/lib/python3.14/site-packages/keepmenu/__main__.py", line 130, in server
    mgr.start()  # pylint: disable=consider-using-with
    ~~~~~~~~~^^
  File "/usr/lib/python3.14/multiprocessing/managers.py", line 570, in start
    self._address = reader.recv()
                    ~~~~~~~~~~~^^
  File "/usr/lib/python3.14/multiprocessing/connection.py", line 256, in recv
    buf = self._recv_bytes()
  File "/usr/lib/python3.14/multiprocessing/connection.py", line 447, in _recv_bytes
    buf = self._recv(4)
  File "/usr/lib/python3.14/multiprocessing/connection.py", line 416, in _recv
    raise EOFError
EOFError

I can also reproduce this with uvx and its Python binary builds:

• uvx -p python3.13 --managed-python keepmenu works
• uvx -p python3.14 --managed-python keepmenu crashes in the same way as above.

[firecat53]

This hopefully was fixed already in 43970a3. The original reporter said the fix worked. Let me know if it doesn't!