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Firefox will not start because "A copy of Firefox is already open. Only one copy of Firefox can be open at a time".

  • 1 reply
  • 1 has this problem
  • 8 views
  • Last reply by cor-el

dknodel2106
dknodel2106
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I had a major crash of Firefox - maybe virus or malware. I think computer is clean now. I deleted all Mozilla/Firefox files I could find and re-install Firefox. Will not run in safe mode (same error). Since I deleted Firefox/Mozilla files, I can not supply crash information/logs :( It runs fine on another computer on my network, this MacBookPro, same OSX and version of Firefox.

Profile Manager?

I had a major crash of Firefox - maybe virus or malware. I think computer is clean now. I deleted all Mozilla/Firefox files I could find and re-install Firefox. Will not run in safe mode (same error). Since I deleted Firefox/Mozilla files, I can not supply crash information/logs :( It runs fine on another computer on my network, this MacBookPro, same OSX and version of Firefox. Profile Manager?

All Replies (1)

cor-el
cor-el
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  • Top 10 Contributor
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Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See: