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Error message: A copy of Thunderbird is already open. Only one copy of Thunderbird can be open.

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42sneakers
42sneakers

I'm trying to move my thunderbird data to a new computer. Both have TBIRD 140.6.0esr installed. Old computer is Mac OS 11.7.2, new one is Mac 15.7.3. I've copied and transferred the files same as Mozilla says to: (user>library>thunderbird folder to same on new computer) I keep getting this error message: A copy of Thunderbird is already open. Only one copy of Thunderbird can be open.

This is a fresh new computer, Thunderbird has never been installed. I am stuck. HELP.

I'm trying to move my thunderbird data to a new computer. Both have TBIRD 140.6.0esr installed. Old computer is Mac OS 11.7.2, new one is Mac 15.7.3. I've copied and transferred the files same as Mozilla says to: (user>library>thunderbird folder to same on new computer) I keep getting this error message: A copy of Thunderbird is already open. Only one copy of Thunderbird can be open. This is a fresh new computer, Thunderbird has never been installed. I am stuck. HELP.

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Mapenzi
Mapenzi
  • Top 10 Contributor

On the new Mac open the Activity Monitor and verify if any Thunderbird application is running. Or click on the Apple symbol in the upper left corner in the menu bar and select "Force quit"

42sneakers
42sneakers Kysymyksen kysyjä

App is not running. App is not in the force quit menu.

I found a workaround by trashing the whole "thunderbird" folder from the User>Library, relaunching the app and then going to Tools> Import to import my old thunderbird profile folder. Sprouted a few grey hairs in the process of figuring this all out but at least my new computer has all my emails now.

Aron Smith
Aron Smith

I’ve seen this happen before. Sometimes Thunderbird thinks it’s still running in the background. Try quitting completely and checking for any hidden Thunderbird processes, then open it again it usually fixes the issue.

Muokattu , muokkaaja Aron Smith

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