Problem: The folder 'Inbox' cannot be compacted ...

[Ravefiend]

My issue is very much like previously reported in e.g. this topic but it keeps annoying me.

Alert: The folder 'Inbox' cannot be compacted because another operation is in progress. Please try again later.

Currently using Thunderbird 52.1.1 (32-bit) but I've had this issue for many years on earlier releases as well. I've read through the Compacting folders page to get more insight in the process and caveats. Still, what bothers me the most is that I cannot explain the root cause.

Some facts:

• IMAP account
• Fairly large Inbox, +- 5000 msg (660MB)
• Large number of message filters on the Inbox, +- 600

When the Alert is shown, the Inbox suddently shows 0 message headers. One has to navigate to another folder and back to the Inbox to see the all messages again. Even more curious is that despite the alert being shown, the Inbox DOES get compacted and deleted messages are removed.

The issue does not always occur and I have not been able to identify the exact steps to reproduce. For some time I've kept the Activity Manager open so whenever I compact my Inbox, I can initially see NO activity being executed. I've tried several things before, incl. removing the msf files, using the Repair folder option and others. Still the issue always reappears after quite quickly after any such actions.

I'm interested to find the root cause of the alert so I'm looking for advise on how to figure out for starters, what's the other operation that is in progress since the Activity Manager does show any onging activity. Any suggestion on how to debug / troubleshoot TB for this issue?

[DanRaisch]

Your situation is quite different from that in the link you referenced because the account in that case was set up as POP and not IMAP.

Do you require access to messages for that account when no Internet access is available or do you access that account from multiple computers?

Do you have Thunderbird set to store messages for that account on the local computer for off-line access? Check that under menu path Tools->Account Settings->Synchronization & Storage->Keep messages for this account on this computer.

As for what other activity might be involved, it could be the updating of the folder index file upon completion of downloading messages from the IMAP server, or it could be the generation of the Global Search index if that option is active (under menu path Tools->Options->Advanced->General->"Enable Global Search and Indexer."

[tanstaafl]

If it gets too annoying one workaround would be to configure Thunderbird to also automatically expunge deleted messages whenever there are 20 of them. That uses a different method than compacting to physically remove "deleted" messages. Its transparent, automatic, and doesn't get blocked by other activity like compacting can. The main reason its not well known is its a IMAP specific. enhancement. See http://kb.mozillazine.org/Deleting_mess ... P_accounts

I'm configured to use it for a different reason. Automatic compacting requires a minimum of 1MB of wasted space and most of my messages are less than 10kb. I like to keep the number of deleted messages low not to save space but to reduce the risk of corruption.

[Ravefiend]

Thanks for the suggestions. I'll look into those and make some changes like excluding my Inbox from my Global Search.

I explicitly do not want these messages to be expunged automatically. I got quite a few emails coming in from mailing lists that gets sorted by my message filters upon retrieval. Still, I want to see the message headers in my Inbox to 'scan' through them if there are any messages of my interest, despite the fact that they have already been Deleted.

[tanstaafl]

I suggest you move most of the messages in the inbox to other folders. Try to keep the inbox under 500 messages. Perhaps you could have your message filters do more sorting, to help keep it under 500. That will reduce the chance of compacting interfering with you, reduce the chances of corruption, and increase performance.

"Still, I want to see the message headers in my Inbox to 'scan' through them if there are any messages of my interest, despite the fact that they have already been Deleted."

That seems incompatible with "when I delete a message" set to move it to trash. I suggest you think about setting it to "just mark it as deleted" instead, and perhaps also customize the main toolbar to add the mail views widget. That would let you easily see all of the mail in the last 5 days (select that in the view widget), with lines drawn through the folder listing for any messages that were deleted. The messages will still be readable despite being deleted. You could also create custom views, that you select as needed. You may find that more useful/convenient than global searches.