Since posting my initial post, I have managed to get Thunderbird to use my old profile instead of the one it had created. (I think the kb should be updated though because that initial screen was quite frightening!)

My next question is: is it okay for me to delete the profile that it created in File Explorer?

Dave

I spoke to soon - under Extensions, Lightning isn't listed on my new computer. And when I tried to install it, I got a message saying that Lightning isn't compatible with my version of Thunderbird. The main reason I use Thunderbird is because Lightning is so good. So presumably I need to revert to an old version of Thunderbird. How can I do this?

Dave

It sounds like you got version 78. Version 78 doesn't need the lightning addon, calendar is built in.

The calendar doesn't work with version 78 because the Provider for Google Calender doesn't work with it. Without the Provider the calendar is useless.

For google, sure.

Quoting from another support article "TbSync 2.16 should work for most providers in 78: https://addons.thunderbird.net/en-us/thunderbird/addon/tbsync/versions/?page=1#version-2.16"

Did you get an error message about provider not working? Or is there some other symptom?

My Calendar didn't load when I followed the procedure in my original post. I then looked up the Provider for Google Calendar and I got a message saying something like: "This version is not compatible with your version of Thunderbird." And on their own webpage it says it only works with versions up to 73. I then saw numerous posts in other forums saying that the Provider for Google Calendar doesn't work any more. So the calendar is useless as far as I'm concerned.

I eventually worked out how to "upgrade" to version 68.11.0 of Thunderbird, which is the version I was running on my old PC, and I ran the procedure in my original post again - and now everything is working, thank goodness. But I've lost a lot of hair and many wasted hours over this.

It's a nightmare - and very arrogant IMO - the way Mozilla keep adding new features that have absolutely nothing to do with security but which break add-ons that their users are completely dependant on. This isn't the first time they've done that but it's by far the worst.

I've turned off automatic updates now, and I just hope to God they don't somehow break that setting as well.

Dave

Sorry - I accidentally posted the same thing twice and I couldn't see any way to delete the duplicate post, so I've edited this one to remove the duplication. And sorry if I made the stress I've been going through over this too obvious but it's how I feel. I really think the developers should be much more considerate towards their users.

Dave

I still have one outstanding question: is it okay for me to delete the profile that Thunderbird created in File Explorer before I told it to use my old profile instead? It is using my old profile now but the one it created is still visible in File Explorer.

Also, please could the developers take on board the fact that users need them to make it possible for people to get important security updates without also getting feature updates that could potentially - and sometimes do - stop their add-ons from working. As it is, I can't afford to risk getting any more of the former in case I also get some more of the latter.

Many thanks for any help you can give me.

Dave

Try to change in THUNDERBIRD preferences editor security.tls.version.min from 3 to 1

From the menu at the top right, go to Options. Scroll all the way to the bottom and click on Config Editor. Skip past the warning. Scroll down until you find security.tls.version.min (or paste security.tls.version.min to upper frame) Double click on it, and set the value to 1

Mozilla disabled TLS 1.0 and 1.1 in the latest versions of Firefox and Thunderbird. Thunderbird 73b and above. This causes issues with anyone connecting via SSL/TLS/StartTLS to services uses 1.1.

Hi kotouc74

I'm not as IT literate as you seem to have assumed.

I understand the first section of your post up to and including "set the value to 1" but I don't understand what changing that setting will do. And I don't have any idea what the last two paragraphs of your post mean.

Please could you explain it in layman's language?

Many thanks

Dave