I'm running Win10 and Thunderbird 128.6.0esr. I wanted to move my profile from C: to a different drive (in my case, the D drive). I Googled and got lots of hits, both on the Thunderbird support site and elsewhere, that seemed to indicate to me that some users were seemingly having issues getting this task completed. Also, looking around in my Windows "AppData" subdirectories, I noticed that there are actually two "profile" directories. For example: C:\Users\xxx\AppData\Local\Thunderbird\Profiles\abcdefgh.default C:\Users\xxx\AppData\Roaming\Thunderbird\Profiles\abcdefgh.default Many of the instructions I found were dated from two years ago or more and only discussed moving one profile directory (the one in "Roaming") and I wondered if, in the interim, there's been an addition of a second profile directory that wasn't being addressed in the "old" instructions I was finding on the Web. So instead of trying any of the suggested procedures I decided to try something else that seemed to be simpler and more straightforward to me. After performing the process I decided to try, testing seems to indicate it works just fine. However, I thought I'd leave this message to ask if there's some issue that can result by doing it as I did. All I did was to create a new directory on my D drive to hold to two profile directories. Inside this new directory, I created two subdirectories called "AppData-Local" and "AppData-Roaming" to hold the two respective profile directories. With Thunderbird closed, I then copied the two original profile directories into their new respective directories on the D drive: D:\Thunderbird Profiles\AppData-Local\abcdefgh.default D:\Thunderbird Profiles\AppData-Roaming\abcdefgh.default Just to be safe, I then renamed the original profile directories under the "...\AppData\..." directory on C: so that if my idea went south, I could just restore the original configuration easily because they weren't deleted. So the original profile directories became... C:\Users\xxx\AppData\Local\Thunderbird\Profiles\abcdefgh.default.delete_me C:\Users\xxx\AppData\Roaming\Thunderbird\Profiles\abcdefgh.default.delete_me All that was left was to open a Windows "cmd" console window (running as administrator) and create a symbolic link in each of the original directories on the C drive that point to the new locations of the directories on the D drive: C:\Users\xxx\AppData\Roaming\Thunderbird\Profiles>mklink /D "abcdefgh.default" "D:\Thunderbird Profiles\AppData-Roaming\abcdefgh.default" C:\Users\xxx\AppData\Local\Thunderbird\Profiles>mklink /D "abcdefgh.default" "D:\Thunderbird Profiles\AppData-Local\abcdefgh.default" (Note that I changed the "current directory" before running each "mklink" command to put the symlink in the right directory.) Then, I started up Thunderbird and... it was as if nothing happened. Everything (old messages, settings, etc.) was still there exactly as before. So far, my limited testing seems to indicate that this process worked without a hitch. I even tried the Thunderbird "backup profile" feature and it created a zip file that seems to contain a subset of the contents of the "Roaming" profile directory, which I suspect is perhaps all that really needs to be saved in a profile backup? Right? Just in case, I haven't deleted the original, but renamed, profile directories yet. I thought I'd post this message and see if anyone has a reason why moving the profile to a different drive by this symlink process is a "big mistake." Or even a "little mistake" for that matter.