What version at the time you wrote this on Dec 11? Please find filterlog.html in your profile directory for that account, and check the file size.

I found the file "filterlog.html" and it is a minimal 1k size. It is only an html shell - no content. It was last updated 12/5/25. So, how do I fix Thunderbird not logging the filtering actions?

shut down thunderbird and delete the file. then try again

Thanks for the suggestion. Sorry to say that did not work. It just created a new file but is still not logging the filter actions. Is there anything else I should try?

https://bugzilla.mozilla.org/show_bug.cgi?id=2001009 reports this for version 145. Are you using version 145 or 146?

I am currently on v146.0.1. Updated a couple of days ago after problem started in hopes it would resolve it.

Is your locale in Thunderbird set to Japanese?

FYI I am in the U.S. using Windows 10 Pro. I can not find a "locale setting" in Thunderbird to verify, but it should not be "Japanese". Language is set to "U.S. English". So, I see I am not the only one with this problem. It appears to have possibly been introduced with the v145 update.

This is fixed in version 148, which ships in beta this week. In another 4 weeks the release version will ship.

Wayne, thanks for following up on this issue and for the heads up. I will look for v148,

Edition Windows 10 Home Version 22H2 Installed on 6/18/2021 OS Build 19045.6809

I too am having a problem with filters not working, "no Log Data" Thunderbird Version 147.0 64 bit