Does the same happen when you start Thunderbird in "troubleshoot mode"? Menu Help > Troubleshoot Mode ....

No, it doesn't happen in that mode:

• I checked the turnoff addons box and 'continued in troubleshoot mode' and it came up with messages showing

It also came up with box showing it needed to compact folders to save 16.2 GB I click compact and it spent a minute doing so with no messages showing, But after it finished, the message headers did come back.

'So now what do I do? Always start or restart in troubleshoot mode?'

Thanks for the suggestion. I had seen that and had clicked disable add-ons but I then had clicked restart, without knowing that that button wasn't troubleshooting. This time I clicked the other button...

Thanks, Bert

I didn't understand whether your thread pane is populated again when you start Thunderbird in normal mode. I think that you hadn't compacted your folders in the last years ....

No, I hadn't restarted in normal mode after trying the troubleshooting mode. When I did just now, it comes up with no messages :(

Also, I see the 16.2 Gb or some large number often, as well as smaller numbers and I do compact often. Seems like something is wrong in the whole compaction process.

What do you suggest now? Thanks, Bert

No, I hadn't restarted in normal mode after trying the troubleshooting mode. When I did just now, it comes up with no messages :(

So when you start TB in troubleshoot mode your thread pane is populates and you can open/read messages? This can mean that one of your add-ons interferes in TB's normal functions. Hardware acceleration could also be th culprit

Also, I see the 16.2 Gb or some large number often, as well as smaller numbers and I do compact often. Seems like something is wrong in the whole compaction process.

Where do you see this 16.2 GB size? Is it the size of a folder or a file? Can you be more precise?

What do you suggest now?

Please read this SUMO help article to understand the difference between troubleshoot mode and normal mode https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird If you use add-ons disable them and restart TB. If the problem persists disable "hardware acceleration" in Settings > General (scroll dawn to the bottom) If this doesn't help restart TB in troubleshoot mode, check ✔︎ Reset toolbars and controls" and click "Make Changes and Restart". If this doesn't help return in Settings > General > Indexing and disable "Enable Global Search and Indexer". The selected Inbox folder in your screen shot contains nearly 88.000 messages. Do a R-click > Properties > General Information ... Which is the size on disk?

I had done the first two those, so I tried the 3rd reset toolbars... and it seems to work. Restarted normally once more and still works, but we'll see after the next compacting...It hasn't asked to compact in the 6 + hours since I reset the toolbars.

The 16.2 Gb and other numbers are the stated size of reduction that the compation needs to tackle. I have it set in Settings to only try compacting if the number is >1Mb See screen shot attached.

The size of that inbox is 26.4Gb, but the disk has 1.2Tb free, so shouldn't be a problem. I would archive some of the older emails, but I've had problems with losing mail when I tried before.

I'll mark it solved if the messages still appear after the next compaction.

Many thanks for your help, couldn't have done it without you.

Bert

An Inbox size of 26.4 GB is gigantic, I've never seen this in any of the Thunderbird forums I'm working for ! In your case it is in an IMAP account, so even if the INBOX file in the Thunderbird profile folder would get corrupt your emails are still preserved on the server. The Inbox folder is not meant to store indefinitely all incoming message or being used as an archive. You can archive messages either with the Thunderbird archive feature or create thematic archives in Local Folders. BTW do you use the mbox or the maildir format to store your messages? Server Settings > Account name > Server Settings > Message Storage... I hope that your problem is solved now and sincerely encourage you to reduce your Inbox size.

Thanks for all the help. The compact folders needed box came up for 5.4Mb and I did it. The messages went away, but came back. Whew! So unless a big size compaction comes along and fails, I think we're back in business.

As to size of inbox, I will cross my fingers and try to archive the past few years. Hate to lose my title of having the biggest inbox you've ever seen :)

As to the mbox vs maildir question, I had no idea, so thanks for the way to find out. The answer is mbox. The inbox and other folders are .msf

You were patient and helpful. Thank you. Bert

Thunderbird's classic "default" message storage format is mbox (or mailbox) which means that all messages of a folder in the folder pane are stored in ONE text file in the profile. So an Inbox text file is constantly modified (updated) when new messages are downloaded, moved or deleted.

When the newer maildir format is chosen, Thunderbird stores each message in a single .eml text file. Comparing mbox vs maildir: when an mboxfile gets corrupt, damage maybe much more important than with a corrupt .eml file.

Please check your error console (ctrl+shift+J) after startup and after selecting a folder. I suspect you will find lines mentioning errors. Perhaps of the form

Uncaught TypeError: .... chrome://messenger/content/about3Pane.js

Thanks Mapenzi. That's enlightening information. How do I safely transition to maildir? I would appreciate your knowledge and help.

Thanks Wayne. I do not see an error like that. I have attached a screen shot of the only errors and a few of the hundreds of warnings that I see when I checked the error console. Any thoughts on the relevance to all these compaction warnings and the problem I've been having? If so, what should I do? Bert

Thanks Mapenzi. That's enlightening information. How do I safely transition to maildir? I would appreciate your knowledge and help.

I've made a search and found this discussion https://support.mozilla.org/en-US/questions/1480541 in which I already had replied to the same question. I just tested the indicated method in a small IMAP account and the transition of 460 messages from mbox to maildir worked rather quickly. It certainly will take more time for the 88.000 messages in your Inbox. To be on the safe side create a backup copy of your 26.4 GB Inbox before launching the transition...