I don't know what you did to get the profile folder to the root of the users folder, but the default location of Tbird's profile folder is in the Roaming (%AppData%) folder. My simplest approach to migrating is as follows:

1. Open the current (new) profile folder, Quit Tbird, select and Delete everything inside it, rendering it EMPTY.
2. Open the old profile folder, select everything, copy-paste them into the new empty profile folder then launch Tbird.

When you use the term "profile folder" do you mean the folder "Thunderbird" or the folder "Profiles"?

I think I have made a rod for my own back. When I installed Thunderbird on the old PC in 2014 I elected to have the profile folder in the user's folder, e.g. in \users\Fred\Thunderbird. The only folder in \users\Fred\Thunderbird is Profiles. Looking in the Roaming Thunderbird folder I see three folders including an empty folder "Profiles".

None of those. The profile folder is a weirdly named subfolder inside the "Profiles" folder. Its name consists of eight random alpha-numeric characters, then a period (.) followed by the name of the profile (e.g "default") then an optional suffix. For example;

• abcd1234.default
• wxyv7890.default-release
• e8dj93yj.default-beta

See Profiles - Where Thunderbird stores your messages and other user data

Thank you so much with speedy responses.

Just to be clear, the Thunderbird installation on the old PC runs perfectly fine. Unfortunately, in the old PC Profiles folder there is no file with any of the name characteristics. There is no folder with "default" in the name and none starting with eight random alpha-numeric characters.

In scrappy notes I see that I used the profile manager to move the "profiles" file (dnqpmwla.default). I think the "Profiles" folder on the old PC in the non-standard location was in fact the "profile folder". I copied the contents of this folder into the folder irs6y97l.default-release on my new PC and loaded Thunderbird to see the expected contents. Thank you so much for helping me. In future if I do something non-standard write up fullsome notes or just stick to the normal configuration - doh.

I've included this note for completeness and to help any other who've dug a similar hole.

Thanks again. regards Tony

In future if I do something non-standard write up fullsome notes or just stick to the normal configuration

That's a good idea. You're welcome.