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Error says Thunderbird running and won't start after closing

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  • 4 have this problem
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  • Last reply by Toad-Hall

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While trying to move my Thunderbird account from an existing Win10 computer to a new Win10 computer I copied my profile to a thumbdrive. After downloading TB on the new computer I copied the profile to the C:\Users\me\AppData\Roaming\Thunderbird\Profiles folder. After starting TB I get the error message "Thunderbird is already running but is not responding. The old Thunderbird must be closed to open a new window". The Task Manager shows one instance of TB running and I close it and try to start TB again with same result. Could my old profile have become corupted during the copy? Its a ~3GB file and took a long time to copy to the thumbdrive. I hope I haven't lost my email and calendar history.

While trying to move my Thunderbird account from an existing Win10 computer to a new Win10 computer I copied my profile to a thumbdrive. After downloading TB on the new computer I copied the profile to the C:\Users\me\AppData\Roaming\Thunderbird\Profiles folder. After starting TB I get the error message "Thunderbird is already running but is not responding. The old Thunderbird must be closed to open a new window". The Task Manager shows one instance of TB running and I close it and try to start TB again with same result. Could my old profile have become corupted during the copy? Its a ~3GB file and took a long time to copy to the thumbdrive. I hope I haven't lost my email and calendar history.

Chosen solution

If Thunderbird had not been closed and you copied the Profile, then there will be a 'parent.lock' file which you have copy pasted into the new Win10 computer.

The 'parent.lock' file is only there when Thunderbird is running and is removed upon closure.

Try this: on new Win10 computer. Make sure Thunderbird is closed. Make sure hidden folders and files are visible

Access C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\Profiles\<Profile name>\

look for a 'parent.lock' file and delete it.

Did this work?

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Toad-Hall
Toad-Hall
  • Top 25 Contributor
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Chosen Solution

If Thunderbird had not been closed and you copied the Profile, then there will be a 'parent.lock' file which you have copy pasted into the new Win10 computer.

The 'parent.lock' file is only there when Thunderbird is running and is removed upon closure.

Try this: on new Win10 computer. Make sure Thunderbird is closed. Make sure hidden folders and files are visible

Access C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\Profiles\<Profile name>\

look for a 'parent.lock' file and delete it.

Did this work?