Moving Thunderbird Backup Profile from Win 7 Pro to Win 11 Pro.

This is something I have had to do several times over the last 20 years but not in a very long time. The directions on the Mozilla site have always been rather straightforward. Not so much at this point. For profiles larger than 2 GB, they suggest doing it manually. These folders were not located on the OS drive as we have that on it's own partition. The OS drive has a "twin" so if a machine's OS got borked, a trip to the BIOS had us up and running. So profiles were stored on networked drive which was backed up.

It directs one to use the export tool to find the profile folder location which in this case is on Drive T:\MozillaProfiles\Thunderbird\Defaults. The instruction state that the file has a name like "abc12defg.default-release." The Defaults folder has many files and folders but also a subfolder named"Profiles" and within that is the noted "xxxxxxx.default" file" )no release) (10.2GB).

I followed the instructions here for "Creating a backup of large profiles"

Made a copy of the contents of the "******default" folder
Copied to a thumb drive
Put the contents in the xxxxxxx.default file on the Win 11 box
Rebooted and launched the program
Say a lot of disk activity and that's about it

Saw several youtube videos with other methods but neither of those worked.

Anyone k ow of any other solutions

It should also work on Thunderbird, when I want to manually backup Firefox, I simply copy all Mozilla folders from the original location (C:\Program Files, C:\ProgramData, C:\Users\username\AppData\Local etc) to the respective folder of the new installation. Then I download Firefox and install it. The folders are detected and I see "upgrade" at the last stage. I click on "upgrade" and after installation everything is back, my theme, my bookmarks, my browsing history and until recently the passwords (in new versions I have to type them again). Do the same with Thunderbird. Copy-paste all folders at their respective location before installing Thunderbird.

That's the procedure I have used in the past. This time I looked at a few videos using compressed files and suggesting that if it's over 2 GB, you need to split them up into separate compressed files. It was also complicated by the fact that %appdata% didn't actually show you where the actual folder was, it was; I had to drill down 2 levels.

After overcoming those obstacles and just doing a copy paste of the profiles, it all went fine. Oh 1 more thing, After 13 years, I didn't remember where TB stored the passwords :), That took another 10 minutes

Before you do anything backup your bookmarks and passwords, just in case.

I have always used this method and it still works.

See the following folders and copy each one that starts with Mozilla Make sure you know where each one came from, don't mix them!

C:\Program Files (64-bit version)
C:\Program Files (x86) (32-bit version)
C:\ProgramData
C:\Users\youruser\AppData\Local
C:\Users\youruser\AppData\LocalLow
C:\Users\youruser\AppData\Roaming

To keep them separate and remember where each one was, I create the folders in backup like this: ProgFiles, ProgFiles(x86), ProgData, AppData_Local, AppData_LocalLow, AppData_Roaming and I copy the "Mozilla..." folder inside the respective one. At the new installation I copy-paste the "Mozilla..." folders at the respective location. These copy-pastes must be done BEFORE installing Firefox or Thunderbird! If done correctly, you should be offered to "upgrade", proceed to copy the appropriate data in Registry and make the program work. I have also done it successfully for Google Chrome and Opera browsers. Old versions of Firefox would keep everything, the theme, the bookmark, the browsing history and even the passwords, Newer versions omit the password for security reasons, that's why I said to backup your bookmarks and passwords separately, just in case, in addition to the copy-paste of the all the program folders. Same for Google Chrome, passwords are not copied, you have to export them separately.

When I moved the Thunderbird profiles to my data drive, it was pretty painless. I copied the entire Thunderbird folder from C:\Users\<name>\AppData\Thunderbird to my data drive. Then I just edited the profiles.ini file on C: to point to my new profile on the data drive. When everything was up and running, I whacked all the profiles in the Profiles folder on the C: drive.

Now when Thunderbird updates, the updates are seamless, it has no problem with the relocated profile location.

Moving to a new computer I just moved my data drive Thunderbird folder and did the same edit to profiles.ini for my fresh install of Thunderbird.