102 was a stable release. Ignore any reference to 103, as that was not an official release. For your protection, I encourage going to settings>general and verify that no update happens without your approval. That is, you do NOT want automatic update. I also suggest creating a backup of your profile - I do this myself for all major upgrades. one way to do that is to: - exit thunderbird - at windows desktop, enter %appdata% in the search bar and press enter key. That should open file explorer at the username\appdata\roaming directory. - highlight the thunderbird folder and copy it to another place on computer or to external media.

David Thanks very much , that sounds a sensible thing to do and put the backup on external media. I assume the folder you mentioned contains all the necessary reload data should a failure occur. I will wait and see if any further information arrives before trying it just in case I open a bag of worms on compatibility. Regards A

here is the info in brief steps:

BACKUP

1. ensure thunderbird is not running
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media

RESTORE

1. ensure thunderbird is installed and NOT running
2. enter %appdata% in search window on task bar and press Enter key
3. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
4. start thunderbird and all should be there

Thanks very much David that seems straight forward and I have located the folder. I assume this is for restoring if I need to go back to V91? Do I need to have a clean install of 102 or can I do an update over the existing. In which case will it pick up all my settings or will I have to redo them manually as several accounts are involved. Or are you suggesting I overwrite 102 with the Roaming folder from 91 ? I understand Address Book Contacts need to be in vcard format, something I am not familiar with. I have some concerns over POP3 working correctly as all my mail uses this format and normally i I try to avoid JavaScript. Thanks for your help to date.

- First, do the suggested backup. That's just in case of problems. Be sure thunderbird is not running when you do it. Also, verify that you have thunderbird set to NOT automatically update. - If your ver 91 is 32-bit, I suggest uninstalling it. That will not delete the profile. If it is 64-bit and offers 102, go that route and skip next step. - To get 102, download and install the initial version, 102.0.1. If there are any updates needed, the first release does it. That release is at this location: Get the EXE version. https://ftp.mozilla.org/pub/thunderbird/releases/102.0.1/win64/en-US/ - After installing, clicking help>about should offer to update to 102.15.1. If so, do it. If it offers a HIGHER number, such as 115. STOP. Instead, download the 102.15.1 yourself and install over the top of the current version. Again, use the EXE version. https://ftp.mozilla.org/pub/thunderbird/releases/102.15.1/win64/en-US/ - when done, this is a good time to repeat the steps from my earlier response on backing up the profile, because it is now different. Having a backup of the profile can eliminate hours and days of frustration if the PC crashes or other unforeseen problems surface.

The addressbook remains as it was, abook.sqlite. 102 is slightly different from 91, but take your time. There are much bigger changes in later releases of 115, 128, and 137. 102 may not suffice forever, but keep it as long as it works well. Take care. Write if you have more questions.