I can only offer a comment: you mention multiple prefs.js files. This may be the problem area. Having multiple indicates one of the PCs is not successful in updating at shutdown. I cannot step deeply into this issue, but I encourage starting with the office PC and checking last update date for each to determine which is correct, and deleting all the others. When shutting down, wait a minute to ensure the prefs.js is update prior to copying to transfer to other pc. As I stated, I can only tread so deep into this, but this seems a likely culprit.

Thank you, david, for your reply. Apart from the cache and startupcache folder, everything in the profiles folder has a modified date from over 20 days to a year or more. I see a total of 26 prefs.js files: prefs.js, prefs-1.js,prefs-2.js,...,prefs-22.js, prefs-computername1.js, prefs-computername1-2.js, prefs-computername2.js computername1 = laptop computername2 = office PC

Opening the prefs.js file, I do not see anything that may cause the templates/tasks to not load. I am at a loss on where they are actually stored that they never get restored/backed up when transferring the full profile folder.

As always, I transfer the folder, not the individual files when I am updating.

re : as I use IMAP, it downloads all the mail on the new system regardless. I thought that it should have the latest mail downloaded as part of the profile folder, is that not the case?

When Thunderbird start up, the first thing it does is synchronise with server to check what is on server and download emails to match server.

Imap emails cannot be copied directly into an imap folder in profile and be accepted. As a heads up - If using a backup or need to get emails back onto a server they need to be copied into the 'Local Folders' folder first and then when you start Thunderbird they can be manually copied from Local Folders into the imap account folder which sychronises with server to upload emails via imap onto server.

Therefore any new mail that was previously downloaded onto office computer but not downloaded to the home computer will not be accepted as it has not previously occurred and therefore you get a proper download when Thunderbird starts. Then relevant files gets updated.

What does this mean for your Imap accounts: You have imap accounts on both office and home computers accessing same mail accounts/email addresses, there is no need to copy any emails as they are already on server. You just start Thunderbird and it updates everything.

If you created new folders when using office computer, then they are on server, so on home computer you just need to use the 'Subscribe' button to select the new folders and then they appear and any emails therein get downloaded.

Imap is the type of account people use if emails are stored on server and they need to access those emails on various devices - either computer and phone or additional computers. It means no copy pasting is necessary to show whatever is on server.

re: Email stored outside of Imap account in eg: Local Folders This is not the same for Pop accounts or anything in the 'Local Folders' account. On office computer, you can copy the 'Local Folders' folder and when you get home, remove the current 'Local Folder' folder and paste the copied 'Local Folder' folder into the 'Mail' folder to replace it.

re: 'prefs' files. Thunderbird only uses the 'prefs.js' file. All other 'prefs-n.js' get created if a problem occurs, so they are previously used prefs files. The one with the highest number was the last one used prior to current 'prefs.js' file. Providing the one with highest number has a good size - it might be worth keeping, but all others can be deleted.

re: calendar data If you are linked up to an external server calendar, then a synchronise would auto update, so no need to copy anything. If you use the default 'home' calendar, you can copy paste this folder: 'calendar-data' making sure to over write the original. It contains the 'local.sqlite' file which is the file you need.

re: folderCache.json There is only one that Thunderbird uses and it's called 'folderCache.json'. It would get updated automatically if you eg: Subscribed to see another folder stored on server.

When pasting in some files it seems they are not overwriting eg: folderCache.json Things get awol when folders have not been previously subscribed or emails not previously downloaded. Allow Thunderbird to do this because you already have Imap accounts and it's already got the ability to do what you require.

re :global-messages-db.sqlite That contains data used in search files, so not exactly a good idea to copy paste it as it may not match whatever emails are current on home computer. It is safe to delete that file as a new accurate one would get created.

re:Address Books On office computer - if they have been updated, you are looking to get copies of those files. But I would suggest whilst thunderbird is running - you 'export' those address books as either .csv files or LDIF. Then they can be imported back into Thunderbird address book on home computer. Whilst it is possible to copy the profile files 'abook.sqlite' (Personal Address Book') and 'history.sqlite' (Collected Addresses) - only those can safely be copy pasted to replace surrent files or directly imported. Any other similar named eg: abook-1.sqlite should only be copy pasted if they already exist on home computer as the data to see them is stored in the 'prefs.js' file which ideally you do not copy paste.

re: Message Filters Each account name folder (imap or pop or Local folder) will contain this file: 'msgFilterRules.dat' It contains the Message Filters you created in the relevant maila ccount. It can be copied if required and pasted into the relevant mail account folder. - Please note: I strongly advise that you create a suitable folder name eg: use part of email address to store when copying because they need to pasted into the correct imap mail account folder overwriting the original or delete old one first before pasting.

So - in a nutshell, it seems you are copy pasting a load of unnecessary stuff and it's causing a load of confusion on Thunderbird.

Allow Thunderbird to download emails. Subscribe to see any new folders on server.

Whilst no problem and perhas quicker to copy a single profile name folder - Suggest you Restrict pasting to:

• 'Local Folders' folder if used
• 'local.sqlite' file OR 'calendar-data' folder
• 'msgFilterRules.dat' if required.
• any address book files if required.

Export address books and then reimport via Thunderbird OR you can copy the address book files eg: abook.sqlite etc and then paste them into home computer or use them to import the address books.

re :Templates: See if repairing the folder sort its out - maybe the index folder needs a fix to see whatever is in the 'Templates' folder.

• Right click on 'Templates' folder and select 'Properties'
• Click on 'Repair Folder' button
• click on 'OK'

Did the repair folder work ?

re: Tasks Check - in Profile name folder for 'calendar-data' folder to see if it got duplicated. It's possible the pasted version has assigned a number to the folder and therefore is not being used; if there is more than one. To test:

• Exit Thunderbird
• Access Profile folder
• rename the 'calendar-data' folder as 'Xcalendar-data' so you do not lose it.
• rename the 'calendar-data-1' (whatever it's called) as 'calendar-data'
• Restart Thunderbird to see if it now locates the Tasks.

Did that work?

Thank you so much Toad-Hall for the comprehensive answer. I understand the IMAP thing better now. I am not using the address book but I do utilize the collected addresses, that is why keeping the abook.sqlite would help. Thank you though for helping me understand the profile folder better. It is good to know that there is a lot of useless stuff that I was copying/pasting which is not necessarily required.

For the templates and the tasks, I will try your suggestions and report back.

Once again, thank you for the help.

Reporting back:

1. Repairing the Templates folder did not work. 2. There is only one "calendar-data" folder. The X trick didn't work, as in the new folder did not transition tasks to the home computer.

One thing I see is that all the files are modified over a month ago, basically when they were uploaded to the USB the first time. The only files that have a recent modified date are the ones in the cache folders.

Is it that Thunderbird is looking at the cache files and then pulling up the data accordingly? But if that's the case, I am still copying (and pasting) the whole profile folder (all the unnecessary stuff) and the home computer still doesn't pull up anything (templates, tasks, appointments etc.).

It sounds to me like you are not getting recent copies on your USB, have you checked the date in there match you work system profile.

Next thing is thunderbird really no longer running when you attempt you copy? While folk think the program is done when the user interface is gone that is a misnomer. Check the task manager ( Ctrl + Shift + Esc )and check that Thunderbird does not appear as a process (that is where applications go once they drop their user interface) and it is not all that uncommon to find Thunderbird hung up there through file contention caused by an antivirus or other file accessing product like a corporate streaming backup or cloud sync of the disk location to one of the various "cloud providers like Microsoft, Google et al.

The multiple prefs.js files indicate there has been a problem and the cause is probably still hanging around the edges somewhere. Any file in a profile with a number as described in the prefs.js indicative of file contention issues of some sort. If it is only files with a JS extension my first guess is antivirus. Also the case with gigabyte sized files as scanning of files that large can take 10 minutes or more.

Thanks, Matt. I close Thunderbird before any copying is done. But I will double check with Task Manager the next time.

I also went ahead and removed all the files (including prefs) that had a computername at their end. Coincidentally the latest modified prefs file is the original prefs.js. After doing this purge, I was able to bring my profile size to less than half. Thunderbird is still loading fine (checked at home) but Templates/Tasks etc. are still missing. I will check that on Monday after doing the same at the Office end.

Hopefully after all this, the copy will transfer everything and not differentiate between the computers.

Thank you again for all the help.