I have already tried many things but i cannot find a solution to this problem. So any help is greatly appreciated. I think it might even be an official "bug" or could be improved.

My Problem:

I have had a convert_submission adhoc task, which couldnt be completet. The error was like "you dont have permission to open this file" so i dont know if the file was corrupt.

I tried to find out what was wrong with the file but i couldn't find out where or what file it was. I then found the sql table "mdl_task_adhoc" with this specific task. I deleted this specific task in hope it would be gone and the other convert_submission tasks could start. (I now know that was pretty stupid and dangerous to just delete something in the db on a live system..).

Now there are still around 200 convert_submission tasks which cannot start because the now deleted one wasnt shutdown/deleted correctly.

The current "error" message from the task logs look like this:

Execute adhoc task: assignfeedback_editpdf\task\convert_submission

Adhoc task id: 40039377

Adhoc task custom data: {"submissionid":"315153","submissionattempt":"0"}

... started 16:56:07. Current memory use 13.2 MB.

Converting submission for user id 14660

Conversion still in progress. Requeueing self to check again.

... used 24 dbqueries

... used 0.012706995010376 seconds

Adhoc task complete: assignfeedback_editpdf\task\convert_submission 

With the tasks in "Ad-Hoc-Tasks":

I tried restarting the whole moodle server (during weekend with less people on it) in hope the locks or whatever it is get resolved but it didnt do anything..

I also tried stopping and starting cron which also didnt help.

I even tried to start all tasks via cli which didnt help either.

It's always just this: 

Conversion still in progress. Requeueing self to check again. 

I think task management could be improved but i would just be happy if i knew how to properly delete this task or reset/restart it so my queue doesnt have the 200 tasks waiting and endlessly queueing..

Thank you in advance for any help!