If Back4 crashes on a restart of the service:

1.The problem may be in e-mails data sources (if any).
If you do not have e-mail data sources, then skip to the step 2.
Disable all the e-mail data sources and then retry to restart the Back4 service. If this fixes the crash, the problem is in the email data source, and it has to be examined. You may want to remove all mails - if possible - from the account, and then restart, or forward the mails to the support desk (contact the support desk for the address to forward mails to).

2.If the step 1 doesn't resolve the crash, or you didn't even had e-mail data sources, move all the files from the input queues somewhere else. If the Back4 crashes also with the empty queues, then skip to the step 3.
If there are many queues, you may want to have ready set of folders to keep such files. Then, attempt to restart Back4. If it starts correctly and keeps going, the problem might be one of the files in the input queues. Put files, one-by-one, back where they were and see if Back4 crashes - if it happens, mail the file to the support desk so it can be analyzed. If you replaced all files in the original input queues and Back4 didn't crash, it means the problem was not in files, but elsewhere - however, the presence of files might prevent a correct restart.

3.If Back4 crashes also with the empty queues, then check the scheduled tasks. Tasks assigned to the generation of preview of corrupted images may cause Back4 to keep crashing. Remove the suspect scheduled task and then retry.

See also

Wire images or text are not imported

Back4 crashing anytime