Faulty cases cannot be deleted (rest api / web gui)

Hello,

I have a few cases in bonita community which have been processed and still have the status "started". I have already tried in vain to change the status to "completed" using the rest api. There are no tasks in the cases that have the status "failed" or "pending".
Deleting the cases using web gui or rest api is also not possible. There is nothing in the log files and in the web gui I get the message

...

• An error has occurred. For more information, check the log file.
• The case has not been deleted.

Is there a possibility to delete the cases directly in the database (postgres) or to set them to completed?

Many greetings
Bodo (bgl)