What happens if you create an exception in your antivirus product for the Thunderbird profile folder. I am guessing there are contention issues caused by on access scanning that are causing the action to fail.

I use Webroot and Malware Bytes. I shut them both down and tried again. Same result - no files deleted when I closed Thunderbird.

Did you restart your system after you politely asked these programs to cease and desist?

If you have a wired internet connection try windows safe mode with networking. Unfortunately I have found a worrying trend with these security products that they are not entirely truthful and requests t cease and desist result it a false statement that they have, while they leave the system non functional so nothing useful can be done of ascertained while they are turned off.

Thanks Matt. I need to point out that this is a recent problem since Webroot, Malware Bytes and Thunderbird have all been on my computer for a very long time. It's a Win 10 machine and getting old in the tooth and I'm actually in the process of moving over to a new Win 11 computer. Just an annoying issue that I don't understand. I could do as you suggest with safe mode but likely wouldn't solve the problem when not in safe mode? It's easier just to manually delete trash which I am able to do.

I had figured there might be some kind of quirky problem with Tbird that could occasionally occur with a long standing installation.