Without viewing your screen it is impossible to know where you made the error. You may have dropped the old profile folder anywhere: Directly into Roaming, into Thunderbird, into Profiles. ..... Please show us screen shots with the contents of the folders Thunderbird and Profiles on the new PC. Also post a screen shot with the contents of the profiles.ini file which you'll find in the Thunderbird folder.

Thank you for the prompt Reply The contents of the Thunderbird folder on the new PC: https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-07-05-08-11-45-bb0963.png https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-07-05-08-11-53-aaea7e.png

The contents of the profiles folder on the new PC: https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/imaghttps://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-07-05-08-12-05-72e3f7.pnges/2025-07-05-08-12-00-6b8fa0.png

Lastly, you've asked for the contents of the profiles.ini folder. I don't see a file with this name in the first or second screenshots above. More info on its location, please.

duplicate

Thank you! We don't need the screen shots of the "Mozilla Thunderbird" program files (the two images on the left) The two images on the right show the contents of your newly created profile folder "uf56a7gd.default-release". We can see that this is pristine profile since the prefs.js file has a size of only 6 kB and the profile contains no directory "Mail" neither "Imapmail".

But what makes my eyebrows raise is a folder with the strange name "zs6jybkq". It furiously sounds like a profile folder name. Please open this folder; if it is empty forget it. If it contains folders and files please show them in a screen shot. I had asked for the contents of the folder "Profiles" and the file "profiles.ini". You'll find them both in ....\AppData\Roaming\thunderbird\. ... (see my picture, it is taken on a Mac but the contents of "thunderbird' are the same) If you see a profiles file instead of a profiles.ini file , that means that your system doesn't display file extensions.

Thanks for your patience. zs6jybkq is my Thunderbird profile from my old computer that I saved to an external HDD. I can send you a three-page screenshot if you wish. Most likely this profile is in this folder from one of my earlier failed attempts to move Thunderbird to my new PC.

First image below is the Roaming folder. Next image is contents of profiles folder. The rl7m7y4f.default folder contains only a 1KB file named times.json. The other folder you've previously mentioned: uf56a7gd.default-release is not 6KB, but rather quite large, as shown in the next two images.

Last image is profiles.ini

Sorry. profiles.ini is below.

Thanks again for your screen shots. So - as I suspected - you dropped the profile folder copy from the old PC directly in the thunderbird directory on the new PC where TB couldn't recognise it. We'll try to repair this as follows: • move the zs6jybkq (old profile) folder to the folder Profiles and rename it in zs6jybkq.default-release • open the Thunderbird profile manager as described in this SUMO article https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#thunderbird:win11:tb128 • in the profile manager window choose "Create profile ...", in the Profile Wizard enter the new profile name, then click "Choose Folder..." and navigate to folder zs6jybkq.default-release in Profiles • select zs6jybkq.default-release, click "Open" and in "Conclusion" click 'Done" You should see your old accounts, messages, address books, ....etc