Do the changes work until you restart Thunderbird? I that is happening, then something is interrupting the shutdown. This can be caused by an anti-virus or VPN, normally. If you look at the profile folder and seen more than one prefs.js file, that is a big clue.

Hi David,

Thank you for your prompt reply. The changes don't work at all, only the ones I make to the servers in Account Settings > Outgoing Server:{pick one of the saved configurations} > "Edit outgoing server...". That is, changes done to the configuration of the selected Outgoing Server are saved. However, as soon as I switch to another section (e.g. Server Settings), this field reverts back to "Outgoing Server: Use Default Server". Thus, I can only really use the Default Server as outgoing server. I also can't create new configurations for new outgoing servers, only the ones that were already saved are there, there are no buttons to create a new outgoing server config.

Also, if I change the color, or the account name, or try to delete the account, nothing changes, even before restarting Thunderbird. That's why I think none of the changes on the Account Settings page I screenshot are saved, but the ones in subpages (like Server Settings and Spam Settings) seem to be working, though I haven't tried altering them for fear of breaking them.

In regard to Thunderbird not shutting down: I did find multiple prefs.js files inside my profile folder, prefs.js, prefs-2.js, prefs-3.js, prefs-4.js. I have a VPN and Kaspersky running, I don't know if this could be the cause

This is very frustrating, I have 60GB in my profile folder, I've been using Thunderbird for all my email accounts for years.

PS: I installed Thunderbird Portable 146.0.1 to a different drive and copied the profile folder, but it behaves identically there.

Now that you mentioned Thunderbird not shutting down correctly, I remember seeing this message multiple times in the past, something like a bug report coming up "Thunderbird didn't shut down correctly, click to send this report". But it hasn't been happening lately.

I opened ProcExplorer and searched for any running Thunderbird instance after shutting it down, I couldn't find any though.

Try shutting down the VPN and either turn off the antivirus or change it to bypass email. Those two issues are the cause of many problems posted here. the fact that you have multiple prefs files is proof that thunderbird is not shutting down properly.

Hi David,

Thanks again for your prompt reply! I paused the AV and bypassed the VPN, but it made no difference.

I also noted that the other `prefs.js` files have as last modified date 2022. I think Thunderbird is shutting down properly, at least for the past few months. I shut it down now multiple times and can't see any running instance of it in task manager or Sysinternals Procexplorer.

I think the culprit might have been an account I added 6 months ago or so. I made some configuration errors, I first added it as POP, but wanted IMAP, then I had to transfer folders and "reconvert" it to IMAP. I think I made a mistake somewhere because I couldn't afterwards delete the POP version of the same email account, I still have both in Thunderbird (but the POP one I changed server settings to 127.0.1.1).

I can't delete it ever since. In fact, if I click "Delete" (the red delete button in my screenshot) in the "account settings" for any of my accounts, nothing happens.

Question: I'm pretty sure the settings file got corrupted. Is there a way to rebuild it? Could a crooked `prefs.js` file be the cause?

It will be easier, faster and more productive to create a new profile (Help/Troubleshooting Info, about:profiles) and add your accounts. (Disable the account hub in Settings/General and add from ≡ - New Account - Email.) The original profile is unaffected, and if the new one works properly, you can transfer address books, local mail etc. from the old to the new. Do this with Kaspersky temporarily removed (not disabled) and the VPN disabled.

Thanks for the recommendation! Oh wait, I think I misunderstood you: you're suggesting that I create a new profile for my current Thunderbird install, I'll try doing this right now.

I thought you were suggesting that I started anew, from scratch. The reason I hesitated so far in starting from scratch is that I have my accounts set up to copy emails to Thunderbird local folders and some emails in local folders only exist there (I deleted them from the server to save space). And there's a bunch of other add-ons and things already set up, but I can do this if there's no other way of fixing the configuration.

If I were to start from scratch, for local folders that have exclusive emails (i.e. emails that don't exist anywhere else outside these local folders), is there a simple way of moving them to the new installation?

Follow sfhowe's direction, Yes, if you're comfortable with Windows FIle Explorer, you can simply cut and paste from one Mail\Local Folders folder to another. Done when Thunderbird not running. On restart, thunderbird will acknowledge them.

It will be easier, faster and more productive to create a new profile (Help/Troubleshooting Info, about:profiles) and add your accounts. (Disable the account hub in Settings/General and add from ≡ - New Account - Email.) The original profile is unaffected, and if the new one works properly, you can transfer address books, local mail etc. from the old to the new. Do this with Kaspersky temporarily removed (not disabled) and the VPN disabled.

I successfully created a new profile following your instructions, sfhowes. To copy the accounts, local folders, addon-ons and settings should I just follow this article or is it perhaps outdated? https://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Thunderbird

It mentions copying the prefs.js file, but could it have a bug there?

I need to first backup the Thunderbird portable. One problem is that its drive is low on space, so I'll have to copy it to an external drive and try to do the changes there.

Thanks again!

Add the accounts one-by-one and test them for saving changes. Install add-ons once all accounts are working. Copy abook.sqlite and history.sqlite from the old profile to the new; other sqlite address books can be imported from Tools/Import. Copy the mbox files from Mail/<popserver> and Mail/Local Folders in the old to Mail/Local Folders in the new.

I recommend not to copy prefs.js to avoid possible corrupted or obsolete entries.