I use KDEnlive (the newest AppImage) on an Kubuntu 22.04 system.

Today, it stopped working, with the simplest operations hanging forever.

For example, when I start kdenlive and do nothing else than quit, it will hang forever.

I wondered whether this is an issue with some old broken configuration or temporary stuff that remains somewhere on my system, but I am not sure whether I removed everything. In any case, it did not help.

I also tried Settinge->Run Config Wizard, but this did not help.

Between the last use and now, the only thing I remember doing that may be relevant was an apt-get dist-upgrade, but I don't know what that could have changed. All other applications I use run without issues.

On a different computer, also using Kubuntu 22.04 in practically the same configuration, everything works as it should.

This makes me believe that indeed some half-finished job or broken configuration files are the reason. But I do not know which ones these could be. How can I debug this issue?

What I have tried so far is delete .config/kdenlive-appimagerc and .config/kdenlive-layoutrc, and the entire .cache/kdenlive directory. However, this did not help.

Try help -> Reset Configuration.

If this is not helping try the following steps:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade.

What are the hardware differences between the 2 PC’s (CPU, graphic, …).

I tried all of this, but unfortunately it did not help.

I fact, kdenlive freezes on both computers, it just happens a bit more often on one of the machines (the dual core (4 threads) freezes more often than the newer one (a faster octocore with 16 threads). It looks to me like there is a race conditions that causes the problem sometimes, but not always.

I also compiled the Master branch of kdenlive from source, but the result is the same as with the AppImage.

Also, it looks to me like there is a problem with illegal/incomplete config or job information that remain somewhere after kdenlive has been run.

Sometimes, kdenlive quits ok on the first run after cache and config files have been deleted, but then hangs when I start it again.

Currently, on the faster machine, I observer the exact opposite behaviour: It does not even start to the splash screen when I run it for the first time after these files have been cleared. I then need to interrupt it with CTRL-C and start it again, which usually is successful.

But even after that when I do some work it occasionally freezes.

I know this is not a very clear description, but because the problem is not 100% repeatable, it is difficult to create a test case.

Both computers run Kubuntu 22.04, one upgraded from 20.04, the other one is a clean install onto a new computer. I don't experience any problem with other applications.

I can’t start AppImage newer then 22.04.2. Something has changed after 22.04.2. Can you try with the AppImage 22.04.2 to check if you have the same problem? All old versions are here: https://download.kde.org/Attic/kdenlive/ .

Same problem, both 22.04.1 and 22.04.2 also hang when I just start and the quit the application.