Bugzilla

Hi Gene,

(In reply to gene smith from comment #108)
> I wouldn't think that (my) change of Bug 163964 would cause internal folder corruption but who knows. I haven't seen it myself, but I mostly use "keep messages only on server".  Will ask Richard Leger who requested the change to do folder discovery earlier and see if he sees problems.

I can confirm I have encountered this Bug 1734847 myself few times in the past 6 months but not recently (in the past month or so) in beta. I could not tell in which version of TB it occurs as I use both beta and ESR in parallel, it has been too long... and it so random and not reproducible that it is very hard to troubleshoot. It happened to me mostly in Inbox folder.

It is not impossible also that I have changed my offline sync options during that period of time, up to few days ago I was set to sync and cache locally only 3 days worth of email for Inbox folder but I have now disabled that feature to work online since.

I noticed in beta that disabling offline mode for Inbox was not always immediately effective the first couple of time it was disabled... the option seem to re-tick itself after closing/re-opening options or TB. Not sure why... I would expect TB to immediately apply the change and delete cache repair the folder as needed. I think you are onto something with your Comment 109... 

Like you I do believe that changing sync (offline options) does not always cause Thunderbird to behave as expected and that the local cache is not "cleared" properly (mbox or else deleted) properly when disabling offline mode. Though I haven't properly troubleshoot nor tested that theory... Disabling offline mode for a specific folder shall cause all cache files to be deleted and folder repaired automatically so only headers of message would remain.

Like you I do not believe that Bug 163964 is the root cause because I seems to recall it was happening before it was fixed and published (for quite a long time maybe past bug report may confirm it). As you may recall, the fix Bug 163964 was also delayed upon my request at the time because end-users were already having issues with beta version keeping re-downloading emails... which is different behaviour from this bug... but touch to the same similar mechanism/files and was possibly due to corrupted mbox/msf file issues or else that even a repair folder would not resolve... some had to manually clear the file on disks to fix if I recall correctly. A specific set of beta version were somehow corrupting the file wihtout TB being able to repair properly in successive updates...

Coming back to this Bug 1734847 it is likely linked to sync feature and changed in it... or corruption of cache files/indexing somehow... or access to them...

I seem to have noticed, when encountering it, that if you click on other emails or switch folder before coming back to the email which content was showing the previous email content, it sometime sort the issue. So it could well be a UI view issue... but I cannot know for sure as random in a blue moon and not reproducible at will...

filip.paczynski seems to suggest that deleting the ImapMail folder fix the issue and that end-users encountering the issue may have used some beta version... which maybe at some point corrupted the locally cached data file in a way that even a repair folder could not fix. Only deleting manually the cached file via File Explorer fixed it. At least for a while...

It may also be happening only after a certain number of email/data is cached in the file... but why so randomly is also very strange...

My suggestion would be to troubleshoot and run tests on what happens every-time the sync options are changed especially via the Option tab and if TB behave like it should. When offline mode is disabled on a folder end-users shall be prompted and asked to for clearing the locally cached data and related files (mbox/msf) or not... or TB do it automatically. If cache data remain as breadcrumbs, TB shall stop using it in online mode.

Nothing definite of course...

Regards,