You can run Thunderbird v68 with the --allow-downgrade commandline switch to downgrade your v78 profile for use with v68. See Unable to use profile when you launch an older version of Thunderbird

Thanks you Stans,

it works perfectly apart from the fact that the ADDRESS BOOK is GONE !!

How can I recover it ?

Please help ! Pietro

Open your profile folder and see if you have a file named abook.mab.bak and another named history.mab.bak. Those are backups of your Personal and Collected addressbooks in the old .mab addressbook format (v78 does not use the mab format, but v68 does. This is one of the major changes introduced in v78). To restore those backups, simply rename them to their original name, e.g abook.mab and history.mab and restart Thunderbird.

I can't help you because I have the same problem; I voluntarily upgraded last night. But more, Thunderbird 78 changed some mail server settings, correcting them didn't help, and it won't retrieve new e-mail. I also trashed Thunderbird by just copying over v.68 from another machine, and you know why that was a mistake. See my separate question here. I will try some of the suggestions in responses above and report back. UPDATE 9/17: it took a few hours to figure out what was going on, but I successfully downgraded to v.68 by first deleting the application, dock icon, and Thunderbird folder in user/library and then replacing them with a working v.68 from another machine (I had upgraded to v.78 on only one of my 3 Macs, albeit the most important desktop). Glad to have a working version back. Also, do you run regular backups? (I should have thought that earlier). You can certainly restore V.68 from a backup. It will be missing any changes since the last backup, but at least you'll have a good working version, and if you use IMAP, all the messages will be there. Also be sure to turn off automatic updates in Thunderbird!! It is under Preferences/Advanced/Updates.

This so-called upgrade should have come with a warning label. Forced calendar and we're disbling your mail archiving tools because we know you;d rather archive one message at a time. And if you don't like it, wait for an up yours response in a support forum.

disbling your mail archiving tools because we know you;d rather archive one message at a time.

You don't need any additional tool to save more than one message. You can simply select ALL the messages you want to save and use the Save As > File option available in the menu or just press the Ctrl+S keyboard shortcut . You can save the selected messages in html, eml or text format.

This so-called upgrade should have come with a warning label. Forced calendar and we're disbling your mail archiving tools because we know you;d rather archive one message at a time. And if you don't like it, wait for an up yours response in a support forum.

100% agree. No upgrade should break existing functionality without a warning. (Even from add-ons; add-ons are an intrinsic part of the Thunderbird ethos!) And no upgrade that might break functionality should make it so difficult to revert!

Open your profile folder and see if you have a file named abook.mab.bak and another named history.mab.bak. Those are backups of your Personal and Collected addressbooks in the old .mab addressbook format (v78 does not use the mab format, but v68 does. This is one of the major changes introduced in v78). To restore those backups, simply rename them to their original name, e.g abook.mab and history.mab and restart Thunderbird.

And what should I make of the fact that only half of my abook.mab files had .bak added. The others remained as abook.mab. Was this a failure of the "upgrade" conversion process?

what should I make of the fact that only half of my abook.mab files had .bak added. The others remained as abook.mab. Was this a failure of the "upgrade" conversion process?

If the file name has .bak then it was converted and you should see the address book listed in the version 78 interface.

If it doesn't have .bak in the filename then it wasn't converted, and we would be interested in knowing the file name so that the issue can be resolved. Please send me a private message with the details.

Stans said

And what should I make of the fact that only half of my abook.mab files had .bak added. The others remained as abook.mab. Was this a failure of the "upgrade" conversion process?

I don't know. I only had one abook.mab file in my profile and a single abook.mab.bak after upgrade. It's not surprising, though, that your case is not the same as mine or the OP's, because we definitely have different setups and anything, internal or external, could have caused this. For example, I have explicitly configured my antivirus to exclude Tbird's profile folder from its real-time protection and scanning so that is doesn't intefere with Tbird's file operations during its normal functioning. Is that the case for you as well? Anyway, if you need further help and the solution offered here is not working for you, then start a thread of your own and you will be assisted. Hijacking someone else's thread is just not ideal. I tend to unfollow solved threads, so your post in a thread you have hijacked could go unnoticed because I obviously won't get a notification for your post.

At least Thunderboird is so flexible an modular that you can do practically everything. This is what I did: - disinstalled the 78 - reinstalled the 68 - downgraded with the "-allow -downgrade" keys - removed all the newly created and empty ".mab" (I guess when running the 68 with the profile not yet downgraded) - renamed all the ".mab.bak" to ".mab" and the old 68 is now back.

Just a trick: Be careful that if you leave the old profile with the "autoupdate" feature "on", as soon as you open the 68 you have the 78 autodownloaded that will be installed automatically the next time you open Thunderbird: to interrupt this vicious circle, jump in the installation folder (C:\Program Files\Mozilla Thunderbird) and delete the folder named "updated" tha you will find there and that contains the 78 just downloaded... ...and don't forget to remove the autoupdate option!

Pietro

So, I:

• Turned off automatic updates in 78
• uninstalled 78
• reinstalled 68
• ran thunderbird.exe -P --allow-downgrade
• removed existing .mab files
• renamed all .mab.bak files to .mab

and now when I try to run thunderbird I get the "You have launched an older version of Thunderbird" and it won't let me go on without creating a new profile. I don't want to create a new profile. What did I do wrong? EDIT: I forgot to mention -- I am running Windows 10 professional

The command is thunderbird.exe --allow-downgrade You have above a "-P" more...

Thank you for your reply. I tried it with thunderbird.exe --allow-downgrade and still got the "You have launched an older version of Thunderbird message." Any other ideas?

Thanks again.

If it doesn't have .bak in the filename then it wasn't converted, and we would be interested in knowing the file name so that the issue can be resolved.

I had address book files abook.mab and abook-1.mab through abook-13.mab, excluding the numbers 2 and 10. All were active, that is, I could browse them under version 68. Roughly half of them had .bak added after the upgrade. I didn't notice any pattern. Unfortunately, I started my downgrade before I looked in the version 78 address book, so I can neither confirm which appeared there, nor which did/didn't have .bak added in the process. However, there were .sqlite files created for all of them.

In case it is significant, after following the process described by others above, only the abook.mab address book appears in my version 68 Address Book interface. All the others, the files are in the profile, but they are not picked up by the application. There must be some file which indicates which MAB files to look for? The upgrade+downgrade process seems to have broken that link.

Further info for anyone who finds this thread and who uses more than the single default address book: The update process also changes the prefs.js file to point to the (newly created) .sqlite address book files. This must be reversed.

So, remove the ".bak" from the backed up address book files (if it was added, which I've previously noted was spotty in my experience). The matching .sqlite files may be removed as well, as version 68 will not use them. Then, it is also necessary to edit the prefs.js file to restore the connection to those restored files. Look for lines of the form user_pref("ldap_2.servers.XXXXXXX.filename", "XXXXX.sqlite"); in which you change the "sqlite" to "mab", and also associated lines of the form user_pref("ldap_2.servers.XXXXXXX.dirType", 101); in which you change the 101 to 2. (I have no deep knowledge of what 101 or 2 mean. I was just restoring what I had in backed up files, and this seems to work.)

This appears to be needed only for address books that you created. The default abook.mab must be hard-wired (I am guessing), so that a downgrade to version 68 automatically reverts to that file.

Thank you for your reply. I tried it with thunderbird.exe --allow-downgrade and still got the "You have launched an older version of Thunderbird message." Any other ideas?

The -p switch launches the profile manager while the --allow-downgrade switch turns off the downgrade protection feature that is responsible for the "You have launched an older version of Thunderbird" prompt. The -p switch is optional if you only have one profile, in which case you won't need to use the profile manager. Copy and paste the command line as follows:

thunderbird.exe --allow-downgrade

lnoland said

Thank you for your reply. I tried it with thunderbird.exe --allow-downgrade and still got the "You have launched an older version of Thunderbird message." Any other ideas?

The -p switch launches the profile manager while the --allow-downgrade switch turns off the downgrade protection feature that is responsible for the "You have launched an older version of Thunderbird" prompt. The -p switch is optional if you only have one profile, in which case you won't need to use the profile manager. Copy and paste the command line as follows:

thunderbird.exe --allow-downgrade

Thank you. I found my problem -- I was attempting to include the switch using Windows 10's search box thinking that it would include it when it launched the command (it included the full text in the search response so I thought that's what it would submit -- not true). So, I opened a command window, moved to the Thunderbird folder and ran the command with switch there and that worked -- or at least it got me to the next step.

Further info for anyone who finds this thread and who uses more than the single default address book: The update process also changes the prefs.js file to point to the (newly created) .sqlite address book files. This must be reversed. . . .

Thanks so much for this information -- I have a number of address books and panicked when they were missing. I was a bit nervous about editing the prefs.js file but I made a backup first.

After making these changes, I still wasn't done. I have a lot of filters defined and many of them are based on whether the sender is in a certain address book or they copy the sender into a certain address book (I think those filters relied on the extension FiltaQuilla). Apparently when I opened Thunderbird without those address books available it reset all the filters to point to an address book which was available which messed up everything. I had to go through all my filters to find the ones affected and put them back (I hope) the way they were.

At any rate, I think I'm up and running again. Thanks, everyone, for your help. And that automatic update setting is staying off.

And for macOS users, to downgrade from Thunderbird=TB v78 into v68:

(1) move the TB v78 "/Applications/Thunderbird.app" into your "Desktop" (aka: "~/Desktop" or "$HOME/Desktop") folder, (2) get the TB v68.12.0 macOS DMG installer-app from TB site : https://ftp.mozilla.org/pub/thunderbird/releases/68.12.0/mac/ (or get last v68),

(3) then open (or double-click on) the DMG file, (4) copy the "Thunderbird.app"(TB.app), & place/paste that inside/into "/Applications" folder, (5) then open up "Terminal" from Utility, & run such command:    "/Applications/Thunderbird.app/Contents/MacOS/thunderbird-bin" --allow-downgrade ... to downgrade your TB v78 profile, to use with the TB v68.

(6) check your contacts, etc in your TB's Address Book : goto TB main-menu > "Window" > "Address Book" ( or press ⇧ + ⌘ + B  (Shift+Command+B) buttons ). if you or macOS user have issues with Address-Book then see user:Stans solution posted above. EDIT: i'm including it in below:

(7) again make sure to set Auto-Update option in TB, to Off/disabled, by selecting this option:   "Check for update, but let me choose whether to install them". To select the above option goto TB "Preferences" ( its inside TB main-menu > "Thunderbird" option (for TB in macOS, etc) . In left-side column/pane select "Advanced" > then select "Update" tab in right-side > then under "Allow Thunderbird to" section, you will see/find "Check for update, but let me choose whether to install them" option.

Credit/Reference : i express THANKS to user:Stans for first+initially posting very helping info.