Handling "Concrete\Core\File\Command\RescanFileTaskCommand" failed

I upgraded one of my concrete sites to the latest version and then ran several automation tasks.

Since then I am getting (more than a couple weeks later) messages under failed messages like: Handling “Concrete\Core\File\Command\RescanFileTaskCommand” failed: File not found at path: 1815/5535/4306/image-20190415135144-1.png

Concrete\Core\Command\Batch\Command\HandleBatchMessageCommand

I am pretty sure this came from the “Generate thumbnails” task I ran.

What is worse is that anytime you do anything in the CMS I get a “Blank error” message screen (error pops up with no info and can only close it). Also it seems to be stopping things from updating - e.g., when I update a page it doesn’t show up in teh site unless I clear the cache. (I’ve also cleared thumbnails).

Any idea on how I can stop this task and/or resolve the problem?

Well it was still running and I saw the “clear tasks” button under current tasks. This solved the immediate problem. It was definitely a problem with the database/files not found and trying to generate a lot of thumbnails. If any ideas on how to clear that out - basically it is going through thousands of images and “not finding” most - process seems to be taking weeks (it was running for a couple weeks before now)