Hi "Profiles" should be a folder containing one or more folders that have a string of letters and numbers for the name followed by .default. So the first thing to do is identify exactly where to find the profile Thunderbird is trying to use: Top menu - or Hamburger menu Click on Help (top menu) or Scroll to the Help menu, and hold until further options open (hamburger menu). Click Troubleshooting Information. In the Application Basics section, Profile Folder, click on Open Folder. This opens Windows Explorer showing the location - drive, path and profile name.

Please report that location here, and the version of Thunderbird you are using.

It is possible to have multiple (string of letters numbers).default folders on your device, but Thunderbird typically only uses one. You can look at the folder you got to when identifying which profile Thunderbird is trying to use, and see whether the files called Mail (or ImapMail) and Sent, and the index files associated with Mail and Sent have any data in them (more than 0 file size).

Next identify which is the actual profile folder that Thunderbird should use. That would be a folder with (string of letters numbers.default) or something you purposely named, that contains Mail and Sent and other files with recent dates and more than 0 size. Where did the migration you used put your oldr profile?

Notice that in some cases when Thunderbird is updated, it needs to change the format of the profile to suit the new version. If that did not happen during the installation of the new version, or if you copied the old profile over the newly created one at some point, you might see a message that the profile is corrupt.

There is a separate setting in Thunderbird that tells it where your Local Folders are - not necessarily the same place as the active profile.

You may find something useful in this article https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data and https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

The good news is - it is quite easy to copy the whole profile over from your old computer - if you stll have it - without using third party software. Good luck, Agnes

Hi Agnes, I appreciate your full response, thank you. On the new laptop Thunderbird doesn't open at all but I went appdata/roaming/Thunderbird/Profiles / zdvmrbnu.default and opened this folder. This starts calendar data, crashes, datareporting, extensions, minidumps etc. This contains no imap mail nor mail file. I notice it does have two .sqlite.corrupt files but I don't know if that means they are corrupt or not! I am afraid I am pretty raw when it comes to behind the scenes in computers so please bear with me! I did however look at my old laptop via the hamburger (terminology new to me but very useful) route and in its profiles I found the default file and it does have imap mail and mail but is totally different from the one I described earlier on the new laptop. The version of Thunderbird is 60.9.1. My intuition is that I should delete the Thunderbird which migrated and install Thunderbird again from the website. I could put the default profile from the old laptop on to an external hard drive if you say it is easy enough to transfer it to the new one. Maybe you could tell me where exactly I put it when I have reinstalled Thunderbird? Hope this makes sense to you. Thanks again, Chris

Hi If you used the third party app to move both the Thunderbird software and profile - and now Thunderbird does not open - then that sounds pretty messed up (to use a technical term...). The new laptop may have an empty or partial file system in Profiles. I don't think you can lose by installing Thunderbird, then moving the profile over. The links I mentioned before tells where to put the profile. There are probably three ways to achieve the result you want. However - you may have trouble if your Thunderbird on the old machine is a much older version than the one you install on the new machine. If that is the case you may need to update Thunderbird on the old machine first, then copy the profile over to the same version of Thunderbird on the new machine. Before you do that - 1) use Thunderbird on the old machine to identify the name of your 'real' profile (hamburger menu - help - troubleshooting info) and make note of that. 2) on the old machine, copy the entire contents of Thunderbird\Roaming, or of Profiles to a safe place. (Note - yours may not be in Roaming as per step 1). If that is too big, you could just copy the current profile (letters&numbers.default folder) that you identified in step 1. 3) use Thunderbird on the old machine to identify where any Local Folders or Archives are located - they may not be in the main profile. a) Options - Account settings - Copies and Folders - I would take a screen shot of that for reference, or write down the location of Archives. b) Options - Account settings - Local folders - again make note of where the Local Directory is. Inside your profile, or somewhere else? If those are not in the same place as your current profile, you may want to copy those as well.

After that, follow the process in https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer The video in that article should help. It assumes copying the entire Roaming folder and all Profiles within it - that should cover everything you need, unless your Local Folders is somewhere else.

Just one more thought - you may have trouble if your Thunderbird on the old machine is a much older version than the one you install on the new machine. Check the version. If that is the case you may need to update Thunderbird on the old machine first, then copy the profile over to the same version of Thunderbird on the new machine. Whatever you do - as long as you have a safe copy of the old profile, someone should be able to get you through transferring it to the new machine.

Agnes

I get: "Your Thunderbird profile cannot be opened. It may be missing or inaccessible" My situation is that I was using Win10 then installed Win7. In Win7 using a profile manager I pointed Thunderbird to the location of the profile. It worked. But since support for Win7 has ended I feel I must go back to Win10. But, now I get the above message. The profile manager in Win10 does point to the location of the profile. I may try to delete the profile in Win10 (being careful not to delete files) and simply create a new profile in Win10 and point to where the profile is.

EDIT. I found that if I delete the profile using the Thunderbird profile manager, then create the profile again in profile manager and point to same location, Thunderbid does now access the profile So, problem solved.

Oh Yay! Glad your problem is solved, and thanks for the update. Agnes