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A copy of Firefox is already open. Only one copy of Firefox can be open at a time -- HOW DO I SOLVE THIS?


I have read the other threads and tried what they suggested and am still unable to solve this.

I am using OSX 10.7.5

I have tried uninstalling and reinstalling firefox. This did not work.

Any suggestions?

Additional System Details


  • User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_5) AppleWebKit/536.26.14 (KHTML, like Gecko) Version/6.0.1 Safari/536.26.14

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  • Top 10 Contributor
  • Moderator
10755 solutions 96800 answers

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

If the new profile works then you can transfer some files from your old profile (if there is one) to that new profile, but be careful not to copy corrupted files.