[Fix] Thunderbird is already running but is not responding

If you get this error: “thunderbird is already running but is not responding” and you can’t start Thunderbird at all, you can try a few things.

From Windows 7: go to C:\Users\\AppData\Roaming\Thunderbird\Profiles\.default
You might need to enable view hidden folders and files.

Delete from there the following files or any you see named like this: .parentlock / parentlock / lock / parent.lock.

Be sure to backup first your profiles folder. Just to be 100% sure.

After that, restart Thunderbird, it should start as normal.

For Windows 10, it’s the same, the path to the Thunderbird profile folder might be a bit different, but it’s the same thing. Do the same steps.