The profile structure has not changed, but Thunderbird does do some "migration" actions between some versions of Thunderbird.

You don't need to do any profile editing. Backup your profile. Then install and run each of the following versions for your OS and language which you will find at http://archive.mozilla.org/pub/thunderbird/releases/ 5.0 for example http://archive.mozilla.org/pub/thunderbird/releases/5.0/win32/en-US/ 12.0.1 (15.0.1 skip) 17.0.8 24.8.0 (38.0.8 skip) 45.8.0 52.9.1

Then do Help > About until you get to version 68. Stay on version 68 until you get prompted to update to version 78.

That's a very old version. You'll have to update it progressively in stages with intermediate major versions untill you get to the latest. They are archived here https://archive.mozilla.org/pub/thunderbird/releases/. Unfortunately, I don't know for sure which intermediate versions you should download, because I haven't been able to find information about which specific versions introduced changes to the profile structure. One of us posted the order in some post here, I'll post it if I find it.

I'd go through the versions as follows; 3.1.20 -> 17.0.11 -> 38.8.0 -> 45.8.0 -> 52.9.1 -> 60.9.1 -> 68.12.1 -> 78.4.1

Those ought to cover all the major releases that have changed the profile structure.

I see Wayne has posted the order while I was composing my reply.

After you get to version 52, Thunderbird will update on its own or if you do Help > About - it is not necessary to do the work of manually downloading.

Note for others, version 45 will no longer do updates.

Thank you both - this very useful, but just to clarify in my own mind, what I want to do is move my Thunderbird usage from a Windows 7 machine to a Windows 10 machine, but keep all the old profile data.

So do you recommend un-installing the v78 version I have just installed on the W10, and go back to the earliest version I can find and install that on the W10 machine, version 5.0 as suggested by Wayne, transferring the contents of the old profile folder into the default profile that 5.0 will create?

Then progressively upgrade in the order suggested until I get to v68, and it should make all the profile changes for me during that process?

Dave

Precisely.

Just to complete the thread (and in case it all disappears when I press 'Solved'!) I woud like to thank Wayne and Stans for very good advice.

I did start by installing v5.0 and used the Profile Manager to create a new Profile, which is in a different disk location than the program. This is because my C drive is quite small, but the E drive has a 1TB drive, and my profile folder is about 35Gb! I copied my old profile over the new one and let everything overwrite. Then I followed the recommended progression and I'm now on V.68.12.1. It is offering me to update to 78.4.0 on 'About', but it hasn't prompted me to update outside of About yet.

Everything is there - all my accounts, aliases, addresses, all my mail from 2007 onward, and I can view messages with images from secure servers without a whole pile of error windows popping up. So I'm very happy - and relieved. Thanks again. Dave

I would make a fresh backup copy of the v68.12.1 profile folder then upgrade to the offered v78 in About.

Thanks for that. I will do. After using v.68 for a day, I have another question. I will search for it as well. I am used to the Tabs being below the navigation buttons. but in these later versions they seem to have moved above that bar, which I find very confusing. Is there a way of restoring the tab bar to where it used to be, under the nav toolbar? David

@stans Just browsing through the new questions, I can see why you recommended taking a backup of my v68 Profile! I have made sure that automatic updates are turned off! Dave