When you downgraded to 78, a new profile was probably created, although you could have opened the beta profile by launching TB with the -p --allow-downgrade command arguments. Copy abook.sqlite and history.sqlite from the beta profile folder to the 78 profile folder to restore Personal Address Book and Collected Addresses.

Hi SFHowes, Many thanks for your answer, but, sorry, my knowledge in computer science is rather poor. My PC runs windows 10. I have found a file 'thunderbird" in app data. In "Profiles" are 2 files : "2ltre8ov.default-release" and "ylichni8.default".

I attach a screen report in .docx format to show you what I have.

I don't see any possibility to transfer one file or another from one version on Tbird to another.

The issue is now that I have appearingly lost all my contacts, a lot of my messages and files.

Thanks a lot for your help

Rgs.

JPB

Your picture shows ../AppData/Local/Thunderbird/Profiles, when the relevant profile folders are in ../AppData/Roaming/Thunderbird/Profiles. There you will find subfolders 2ltre8ov.default-release and ylichni8.default. The one with your contacts is probably the one with the largest abook.sqlite and history.sqlite.

You could also close TB, open a Run window (Windowskey+R), and type this command:

thunderbird.exe -p --allow-downgrade

to launch Profile Manager. Choose the profile that was used by TB beta, then OK, and see if all your data is shown.

Hi, I have reached the right "profiles" as you said, but I have only "default-release" and "default". I am on "default-release", I try on "default", I have recuperated all my local files, but my adress book stays empty. If I go to subfolders 2ltre8ov.default-release and ylichni8.default, maybe my contacts are there, but how to do to restore them ? Whatever, many thanks for your help. Best rgds.

Close TB, rename abook.sqlite and history.sqlite, rename abook.mab.bak to abook.mab and history.mab.bak to history.mab, then restart TB and see if your Personal Address Book and Collected Addresses are shown.

Thanks, but there is only one thing missing or I did not understand well : you tell me to rename abook.sqlite and history. sqlite, but what for names to give them ? Anyone with .sqlite or else ?

But where is everything of this ? I send you what I have seen now in a.docx document attached.

Moreoverre all this mess, when wrote an E-mail to some one the adress of whom was anywhere, I only needed to write the first letter and the adress came. Now I have to type anew all the adresses even the most familiar ones.

Thanks once again for your help because itr me now very hard, I have lost a lot of time.

Best rgds.

Rename the existing abook.sqlite to abook.sqlite.old and history.sqlite to history.sqlite.old. This will allow TB to create new files when it restarts and converts the .mab files to .sqlite files.

You first picture shows the Local directory, and can be ignored since it mainly contains cached data.