Folder corruption on 94.0b1 (64-bit) Windows 10

Folder corruption on 94.0b1 (64-bit) Windows 10

In the last week folder corruption has become common which is very worrying. Emails appear to become duplicated but on folder repair emails get lost totally.

This has happened on the inbox repeatedly, even after compacting, rebuilding, and emptying.

It has also happened on the Sent folder plus local folders.

Is this a known new problem? (I could not see it listed here.)

If this persists I will have to migrate elsewhere. I looked at Mailbird but that can’t import the Thunderbird local folders tree. I have thousands of folders and hundreds of thousands of emails stored which appear to be at risk.

Any suggestions please? Best would be a Thunderbird fix, but in the absence of that what alternative can best preserve my history?

Twice emails have reappeared in a Sent folder which had been emptied and compacted!


I see that b2 issued on 9 October included “Stability improvements” in the fixes. But no details.

Have you tried repairing the folder?

Right-click on it.
Select Properties > Repair Folder

Yes thanks. Repeatedly. At times repairing the folder caused emails to appear to be duplicated and others to disappear.

Though just now my Inbox became corrupted again (with b2) and in this instance repair did seem to help. For now!

No. The inbox repair caused emails to be lost. I have had to fetch them from the server again.

This is bad.

Sadly I have given up on Thunderbird after 15 years and am currently trying eM Client which did import my local folders unlike MailBird which did not.

Beta isn’t a place to be judging stability and reliability.

Hopefully you had also tested with Windows and Thunderbird started in
safe mode.

True. My mistake on both counts.

I’m having the same problem. My emails are now a mess. Each email now that I preview has a bunch of other emails appended to it, including their headers. Loading a message now can take a few minutes because they are now huge. My machine starts thrashing memory. I just tried loading an email and Thunderbird is consuming 23 GB of memory at the moment and growing.