By default on downgrade (installing an older version of TB as the one already installed) TB show you a message that you can't use same profile and probably you have created another profile (empty one?) and that's why you have this issue.

Assuming you have windows OS then you can try this: go to run (search run, select that run app) and write on that small field this: thunderbird -p --allow-downgrade It will open "Profile Manager" - here select the old profile which was upgraded and that you could not use it on the downgraded version. All your data should be there except email addresses from the address book.

To add also those email addresses back follow below steps: At the top right of the Thunderbird window, click the menu button (or use the regular menu at the top), then select Help: Troubleshooting Information. Click on Open Folder (if you have multiple options click on the one on the profile zone). Close TB. On the folder opened by TB - you will find the old files which manage that information with extension .mab.bak - those files (abook and history) you need to: -rename them to .mab (so delete the .bak) -so you can do that rename you will need the files with same name/extension already in that folder to move them to desktop? or anywhere else -also move to desktop abook.sqlite and history.sqlite Start TB

Hi svlad2009: ...and thanks for trying to help.

I've followed exactly your advice but unfortunately - it led me to one of many other 'dead-ends' ... Let me just summarize my situation: - I'm running WIN 7-Home Premium, on PC Intel Pentium D, and have the downgraded empty Thunderbird Ver 68 from 78 without bookmarks + messages + previous general settings installed.

- after running the thunderbird -p --allow-downgrade, I've got the screen containing 2 files: 'default' while running resulted in msg.: 'Your Thunderbird profile cannot be loaded. It may be missing or inaccessible', and by trying the other 'default-release' file resulted in getting me back to my EMPTY downgraded Ver 68 ...! I'm enclosing an image of the first step - the other step I did NOT even tried because I'm obviously in a completely wrong place, right ...? PLEASE HELP me find out where are we at this point ...?!? Thanks. Tony H.

Hi svlad2009: I'd like to add to my previous response to you and ask a further question: - when I've opened the profile it only lists the regular .mab-files NOT for instance the '.mab.back' files (and probably all other files too!) so - those are files RELATED ONLY to the EMPTY downgraded 68 version NOT the PREVIOUS version files, don't you think ...?!?

- based on all this confusion, does anyone know where are located SPECIFICALLY the copies of ALL the PREVIOUS Versions of Thunderbird, INCLUDING the most Updated Version 78 files ...? In case we will NOT be able to successfully resolve these extremely confusing issues of 'downgrading to previous version' process - I might be forced to go back to the 78-version because in spite of disliking it, AT LEAST it was working properly in my PC-configuration as compared to numerous problems by MANY other users ...! I'd appreciate your answers to my above inquiries, please! Tony H.

On the general profile folder how many "normal" folders do you see? Are more than 2? To open that general folder open run and copy-paste-enter this text: %appdata%\Thunderbird\Profiles

I'm asking for something instead of replying to your question so I can try to understand what happened on your side. Cause if you don't have .bak files then this could mean you did not upgraded to tb78 from tb68 but something different happened...

Hi svlad2009: I have only ONE profile - I'll try to enclose an image of it, or at least copy the contents, will it work ?!? I've opened it and this profile-folder does NOT contain any '.mab.back' files, the files look only related to my present-EMPTY downgraded 68 version ...! Please advise about the next steps ... Thanks ...!

Hi: I've POSITIVELY UPGRADED (not willingly, of course!) from 68 to 78 version, and strangely the new version WORKED WITHOUT LOOSING anything - BUT after I downgraded BACK to 68 version, I've got ONLY the 'EMPTY' 68-ver. back! IMPORTANT: I've read in 78-ver description that the .bak files are no longer used OR used in a different way - please explain this ...?!? Can you at least tell me WHERE can I find in my PC the back-copy of the 'downgraded Ver 78' complete with bookmarks & all of the other original data & settings ...? You were right stating before that I must have during downgrading to ver 68 selected to 'create new profile' by not having other choice & instruction info ...! Please advise further ...

Your picture is from profile folder but not from %appdata%\Thunderbird\Profiles Can you add a picture also with folders that are there - in %appdata%\Thunderbird\Profiles ?

re :I've POSITIVELY UPGRADED (not willingly, of course!) from 68 to 78 version, and strangely the new version WORKED WITHOUT LOOSING anything How did you get to be using version 78 in the first place ? It would work on the original profile because it has been upgraded to work on that 78 version.

re: - BUT after I downgraded BACK to 68 version, I've got ONLY the 'EMPTY' 68-ver. back! Sounds like you tried to go back to a previous version before you knew the correct procedure on what to do. Perhaps you had not read all the Help Articles or Release Notes. Perhaps you uninstalled and reinstalled just like you have always done in the past. In which case, an auto start of an earlier version would produce a clean new empty profile as it cannot use the original. Profiles are not backward compatible since the start of verson 68 unless a very specific procedure is done right from the start. You have to start Thunderbird with a specific instruction, if you did not do it correctly the first time then you would see a blank new profile.

This explains the situation you find yourself. It does not mean data is lost.

So basically, I think it is not showing you anything because it's not looking at the old profile. The image you posted says the name of the profile is '*.default-release' I would bet you have more than one profile in the 'appdata'/'Roaming'/Thunderbird/'Profiles' folder.

If I were you, I would use the blank profile and recreate the mail accounts. Once this has been done, you can then copy and paste mbox files etc from one profile to the other. But I would not do this without advise first.

Is there any good reason why you are not using version 78 when you say it was working perfectly ok? It would help to know why you wanted to go back.

Hi Toad-Hall: The main reason was the different overall layout appearance which has made it less easy for me to orient myself in selecting various Options as compared to my pretty detailed & specific layout/set-up of my previous version. In other words, while considering to make any version changes I definitely go by the common rule: 'Don't try to repair thing which ain't broken' ---> if a new version does NOT improve anything in the specific Program area/s - why to change it?

I strongly feel that the time could be much better utilized by improving the part of a design which prevents significant users confusion like in the case of the 'Dedicated PROFILE design' used during a downgrading-process, resulting in numerous cases of 'bookmarks + news + general settings' loss, in other words: otherwise a good idea of 'Dedicated PROFILE design', why not to make it as really 'Dedicated PROFILE' without missing the most critical data of the previous version.