With 'mentioned above' I refer to this solved problem: https://support.mozilla.org/nl/questions/1038911

crash report do not appear for hangs. From what I hear you saying your program is simply freezing (hanging)

Are you using anti virus software?

Please start Thunderbird while holding the shift key (Safe mode) and see if anything is different.

Hi Matt,

Thanks for your reply. Tb hangs within 8 seconds after startup (Apple rainbow wheel appears). Starting in Safe Mode doesn't change that.

The problem seems to be related with a full disk message that I got earlier. I made more disk space (now about 35 GB) and Tb started working for a few days and then it hung at the exact same way. At one time I was able to use the Compact Now function and compacted mail with a total size of 245 MB. Then I could use Tb during that session. At the next startup Tb hung again...

So there is a relation with this full disk message and a lot of mail in Tb (although I think it is not extremely much).

Do you have a clue what to do?

Are you using anti virus software?

No, I'm not using virus software. It has to do with disk space, which is enough right now, but Tb doesn't seem to be convinced I think ;)

From the Thunderbird > preferences menu select Advanced > Network and disk space. Set the compact threshold low, say 1 MB From the file menu select compact.

Compacting with that low threshold should capture all your folders. Compacting has more uses that just freeing space. Every email in the store is moved and a completely new index is written. The result is it will get rid of file corruption in either, but in the case of corruption mails sometime go along with the process.

Hopefully that will clear the issue.

IF not open the profile folder and move the panacea.dat file, the session.json file and the foldertree.Json file somewhere else. They are all cache files and will be recreated on startup.

I originally wrote to delete them, but then though that with a slower startup they might be needed if startup does not complete before the hang to speed it up again.

It didn't help Matt. I had to startup Tb in offline mode by using Apple's Terminal and the string "/Applications/Thunderbird.app/Contents/MacOS/thunderbird-bin -offline". Then I made the changes you suggested. After a relaunch Tb hung again.

I cannot find the files you named. Via Terminal I switched viewing hidden files on (string: "defaults write com.apple.finder AppleShowAllFiles YES") and then looked for the file names via Spotlight. None found, also the folder Profile folder cannot be found...

go to the help menu. select troubleshooting information. Click on the show profile button. Finder should open in the profile folder and the files I referenced should be in the selected folder.

Make sure to close Thunderbird before doing any deletions or removals.

Did follow your tips on removing the files to another location (after Tb was closed). It did not help...it still hangs at about the same time after startup...

I've discovered something new in this hanging thing by Tb. It hangs when I move the mouse cursor, say around 3 seconds after I've moved it... If I don't move it, Tb does not hang (showing the Apple rainbow wheel). Tb also hangs when I give a random command like Cmd+N (for a new e-mail). So when giving a command in Tb, it hangs.

Does this give you more insight Matt?

Hi Matt,

I am really through my options now. I've made a new profile and copied some of the mails from my old profile to this one. Now the new profile hangs too... In my old profile the inbox folder had some 20,000 mails in it. Too much? Is there a solution or should I better switch to a different mail program?

Do you have a cordless mouse?

Have you checked your disk for errors? As Thunderbird tends to use more disk space for data than most programs and is constantly reading and writing fairly large files it is more prone to seeing disk errors first.

I've got an cordless mouse (is this a joke?) and my disks are fine (checked them with Disk Aid).

I've decided to go with Apple's Mail. The problems with Tb are taking some weeks now and I cannot search for answers any longer.

Thanks for trying to help me Matt!