I'm looking for the reason for two errored Universe tasks because of:

"Process still present 5 min after writing finish file; aborting"

https://universeathome.pl/universe/result.php?resultid=182944576
https://universeathome.pl/universe/result.php?resultid=182857644

And what might be the solution?

This is on a new Raspberry Pi 4 host. I'm only running on 3 of the 4 cores so as to leave one core free for system housekeeping. Haven't run into similar errors on the other projects running on the host.

Have any tasks finished OK?

The 2nd post in this thread is about the same message: Very short tasks

Perhaps try just one, and see if it works.
At least it will provide some data to think about.

Yes, I have finished many tasks already with no issues. The main difference between the failed ones and my successful one are the failed ones ran 1.5-2X slower than normal.
I don't have any concept of what a "short task" at LHC looks like. Never ran the project.

Sorry, it was just these 2 lines:
Process still present 5 min after writing finish file; aborting
This often indicates an overloaded system.

The other thing that I thought of, was that your 2 that failed may have been "bad" in some way when issued.

I think it was an overloaded system. Even with only 3 cpu cores loaded by BOINC I had just started Universe up on the Pi 4 and it was running all 3 cores on Universe tasks to start the REC rebalancing against my other projects. Once the system dropped down to only 2 Universe tasks and another task from a different project the tasks all completed properly.

I have since put in a app_config restriction to two tasks so should not have the issue again going forward.

I'll call this solved.