Public bug reported:
Apostrophe 3.4-2 from the Ubuntu 26.04 repository is not compatible with
Python 3.14's default multiprocessing start method (`forkserver`).
Environment:
* Ubuntu 26.04 LTS (Resolute)
* GNOME 50.1
* Python 3.14.4
* GTK 4.22.4
* libadwaita 1.9.1
* Apostrophe 3.4-2
The multiprocessing start method is:
```text
forkserver
```
confirmed with:
```bash
python3 -c "import multiprocessing as mp; print(mp.get_start_method())"
```
Launching Apostrophe produces:
```text
TypeError: cannot pickle 'ApostropheTextView' object
when serializing dict item 'textview'
when serializing apostrophe.text_view_markup_handler.MarkupHandler state
```
followed by:
```text
AttributeError: 'ApostropheTextView' object has no attribute 'markup'
```
The problem is reproducible with the Ubuntu package.
The root cause appears to be Python 3.14 changing the POSIX
multiprocessing default from `fork` to `forkserver`. Apostrophe's
`MarkupHandler` starts a multiprocessing process involving the GTK
`ApostropheTextView` object, which cannot be pickled.
A workaround is to force the old `fork` start method before launching
the application:
```python
multiprocessing.set_start_method("fork")
```
This is also the workaround documented in the upstream Apostrophe issue.
Upstream Apostrophe issue #669 tracks this Python 3.14 compatibility
problem:
https://gitlab.gnome.org/World/apostrophe/-/work_items/669
Upstream issue #674, specifically concerning Ubuntu 26.04, was closed by
the Apostrophe maintainer as a duplicate of #669, with the
recommendation to report the packaging problem to Ubuntu.
There is also an existing Python 3.14 compatibility patch in Arch
Linux's Apostrophe package (3.4-3), which applies the same
`multiprocessing.set_start_method('fork')` workaround.
Please consider applying an appropriate Python 3.14 compatibility fix to
the Ubuntu `apostrophe` package.
** Affects: apostrophe (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2163127
Title:
Apostrophe 3.4-2 fails with Python 3.14 forkserver on Ubuntu 26.04
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