Web-greeter unable to run, looks related to Qt5 EOL and `qt5-webengine` deprecation

[tuurep]

@JezerM we have a big problem

Environment

• OS: Arch Linux 6.17.7-arch1-1
• 3.5.3
• 1.32.0

Bug description

(TL;DR unable to launch)

When booting the system, the console cursor top left and mouse cursor alternate a few times and then it's stuck on the console cursor.

Using another greeter, such as lightdm-gtk-greeter allows me to get to my X session, to workaround this.

Running web-greeter in a terminal gives this output:

Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/usr/lib/web-greeter/__main__.py", line 121, in <module>
    import globales
  File "/usr/lib/web-greeter/globales.py", line 3, in <module>
    from bridge import Config, Greeter, ThemeUtils
  File "/usr/lib/web-greeter/bridge/__init__.py", line 154, in <module>
    from .Greeter import Greeter
  File "/usr/lib/web-greeter/bridge/Greeter.py", line 41, in <module>
    from browser.error_prompt import Dialog, general_error_prompt
  File "/usr/lib/web-greeter/browser/error_prompt.py", line 38, in <module>
    from PyQt5.QtWebEngineWidgets import QWebEnginePage
ImportError: libicui18n.so.76: cannot open shared object file: No such file or directory

This is relevant:

$ ls -l /usr/lib/libicui18n.so
lrwxrwxrwx 1 root root 18 Nov  4 17:46 /usr/lib/libicui18n.so -> libicui18n.so.78.1

Steps to reproduce

Use web-greeter as lightdm greeter and reboot, but be sure you know how to recover with a tty.

Expected behavior

Launch greeter.

Investigation

Arch Linux mailing list: Dropping qt5-webengine:

https://lists.archlinux.org/archives/list/arch-dev-public@lists.archlinux.org/thread/U45C4RAW4IXVLO376XGFNLEGGFFXCULV/

Hi,
Qt5 is EOL since May. In particular, qt5-webengine's Chromium ships with unfixed vulnerabilities. Its code is bitrotting, which also makes it a costly package to maintain due to the frequent API changes in its dependencies (I had to give up on system ffpmeg and switch to its ancient bundled version, and currently doesn't build against ICU 78). I therefore think it's wise to drop it from our repos. Its remaining reverse dependencies are:

csoundqt - can be built without it by disabling remote debugging support, MR at [1]
fcitx-libpinyin - archived upstream for over a year
globalprotect-openconnect - very out of date, a new version switching to wbkitgtk and rust is available in testing.
kchmviewer - dead upstream (no activity in 4 years)
qmc2 - dead upstream (no activity in 1.5 years)
wiznote - dead upstream (no activity in 4 years)
openshot - the only case of a (semi-)maintained application still unported to Qt6 - there was an attempt 3 years ago [2] aborted due to some drama and no signs of new efforts since then, porting is non-trivial.

If there are no objections (that include an offer to pick up maintenance of the package), I will drop it and all its unported reverse dependencies in a few days.

[1] https://gitlab.archlinux.org/archlinux/packaging/packages/csoundqt/-/merge_requests/1
[2] OpenShot/openshot-qt#4836

AUR qt5-webengine is getting a lot of comments, because it's a dependency to build Davinci Resolve.

This commit looks directly relevant to the ICU76 - ICU78 mismatch (even if I am not sure what that means):

https://aur.archlinux.org/cgit/aur.git/commit/PKGBUILD?h=qt5-webengine&id=db172a6f1565e80ce7cf78d4e3371032a9b7cd9c

[JezerM]

Hi! I'm aware of this issue, and I actually tried to migrate from PyQt5 to PySide6 in the pyside6 branch.

However I can't really test this because I don't have a Linux machine anymore, and the virtualization through qemu in macOS is giving me some OpenGL issues for Qt6 apps. I will try to make my old laptop to work in the next days so I can try the pyside6 migration.

[tuurep]

Hey sounds great,

seeing as it was migrated to uv, if the pyside6 branch can be currently built, could you give me advice how to build it?

My first time dealing with a uv project :)

[JezerM]

Sure~

Installing dependencies

After you have installed uv, run uv sync inside the web-greeter directory in the pyside6 branch.

cd web-greeter
git switch pyside6
uv sync

This will install any dependency like PyGObject and Pyside6.

Build

1. Make sure that the src/resources/js/bundle.js file exists, if it doesn't, create it manually.
2. Run pyside6-project build for building the required files for PySide6, for example the resources.py file required for injecting the JS files in the web context.
3. Build the screensaver shared library

cat src/resources/js/ThemeUtils.js src/resources/js/bootstrap.js src/resources/js/GreeterComm.js > src/resources/js/bundle.js

pyside6-project build

gcc src/bindings/screensaver.c -o src/bindings/_screensaver.so -shared -lX11 -lxcb

Run

uv run src/__main__.py

You will need an existing theme and configuration to be at the expected places, so if it happens to run, make sure you also have a theme.

Some stuff was successfully migrated to PySide6, as well as replacing some deprecated dependencies with newer ones. However I'm still not able to test the UI and check if every component is in place and working. In theory the bridge for Web<=>LightDM should work.

[tuurep]

Thank you I got quite far with that,

Though it seems like uv run pyside6-project build is better vs. pyside6-project build?

On uv run src/__main__.py it closes after a brief black window

Output of uv run src/__main__.py --debug:

uv run src/__main__.py --debug
2025-11-13 04:07:13 [ ERROR ] Greeter - Greeter.py:98 : __init__ | lightdm_greeter_error: Unable to determine socket to daemon (1)

** (process:239147): CRITICAL **: 04:07:14.570: lightdm_greeter_ensure_shared_data_dir_sync: assertion 'priv->connected' failed
2025-11-13 04:07:14 [ DEBUG ] Greeter - Greeter.py:116 : __init__ | LightDM API connected
Traceback (most recent call last):
  File "/home/tuure/projects/web-greeter/src/__main__.py", line 138, in <module>
    globales.greeter = Browser(app)
                       ~~~~~~~^^^^^
  File "/home/tuure/projects/web-greeter/src/browser/browser.py", line 249, in __init__
    super().__init__(application)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/home/tuure/projects/web-greeter/src/browser/browser.py", line 104, in __init__
    self.windows = self.create_windows()
                   ~~~~~~~~~~~~~~~~~~~^^
  File "/home/tuure/projects/web-greeter/src/browser/browser.py", line 148, in create_windows
    window = BrowserWindow(
        QRect(
    ...<5 lines>...
        web_greeter_config["config"]["greeter"]["debug_mode"]
    )
  File "/home/tuure/projects/web-greeter/src/browser/window.py", line 167, in __init__
    self._init_devtools()
    ~~~~~~~~~~~~~~~~~~~^^
  File "/home/tuure/projects/web-greeter/src/browser/window.py", line 246, in _init_devtools
    inspect_element_action = self.win_page.action(self.win_page.InspectElement)
                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'WebPage' object has no attribute 'InspectElement'

But:

1. It's a work in progress, don't worry
2. I need to learn more about uv

[JezerM]

Yeah, I can't even get to getting that error. There's still a lot to do.

About pyside6-project build vs uv run pyside6-project build, it depends. If you run it with just uv run, it will only take the pyside6 tools context, no other dependencies included (like if it were isolated in another venv), so it could fail. Running pyside6-project directly doesn't force a venv so it runs with the already installed dependencies.

[tuurep]

Oh ok, additional context why I said it's "better":

I needed another dependency, pyside6-tools-wrappers to have the script pyside6-project which was extra confusing

[JezerM]

Oh, true. In that case, then yeah it's better to just run uv run pyside6-project build.

[JezerM]

Got my old laptop to work, so I'm gonna start working on fixing all the pyside6 migration issues.

[tuurep]

Awesome :) Let me know whether to test anything.

[tuurep]

HP stands for Hinge Problems confirmed btw

[JezerM]

Btw, I'm gonna bump the web-greeter version to v4 with these changes. I created a PR for tracking all changes and my TODO list: #89