[Linux] "Waterfox is already running, but not responding" when trying to open an URL from another application

[RJVB]

What happened?

Every now and then Waterfox (like Firefox itself) stops responding to external requests to open an URL, and posts this instead:

I can't say if it's related, but the last entries in the logfile that receives the Waterfox terminal output are

[Parent 24488, Main Thread] WARNING: Failed to measure available space: The specified location is not supported: 'glib warning', file /home/runner/work/waterfox/waterfox/toolkit/xre/nsSigHandlers.cpp:201

(waterfox:24488): Gtk-WARNING **: 16:22:04.536: Failed to measure available space: The specified location is not supported
[Parent 24488, Main Thread] WARNING: Failed to measure available space: The specified location is not supported: 'glib warning', file /home/runner/work/waterfox/waterfox/toolkit/xre/nsSigHandlers.cpp:201

(waterfox:24488): Gtk-WARNING **: 16:22:04.537: Failed to measure available space: The specified location is not supported

I'm reporting it here because I use Waterfox full-time nowadays and hope to have a bit more luck in getting some assistance to figure out why this happens here then I would probably get if I reported it upstream. The issue is annoying because it forces me to restart the browser when I just want to open a link quickly, all the more so because for the rest the browser continues to work just fine.

Reproducible?

• [ ] I have checked that this issue cannot be reproduced on Mozilla Firefox.

Version

6.6.4 20251008135142 20251008135142

What platform are you seeing the problem on?

Linux

[RJVB]

On a hunch I launched qdbusviewer and clicked on the org.mozilla.waterfox.??? service. Nothing happened until the log panel finally showed

Error: Call to object / at org.mozilla.waterfox.L2hvbWUvYmVydGluLy53YXRlcmZveC93YXRlcmxleC5kZXYtZWRpdGlvbi1kZWZhdWx0: org.freedesktop.DBus.Error.NoReply (Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.) failed