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Error message - "A copy of firefox is already open. Only one copy of firefox can be open at a time" but there is no firefox window open.

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  • Last reply by Shadow110

singer.kirsten
singer.kirsten
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Computer crashed suddenly (Macbook Pro). I was able to restart all programs except Firefox. I unistalled and re-downloaded FF, but when I try to open the application, I receive the error "A copy of firefox is already open. Only one copy of firefox can be open at a time". However, there are no other copies of FF open since technically it was uninstalled.

Computer crashed suddenly (Macbook Pro). I was able to restart all programs except Firefox. I unistalled and re-downloaded FF, but when I try to open the application, I receive the error "A copy of firefox is already open. Only one copy of firefox can be open at a time". However, there are no other copies of FF open since technically it was uninstalled.

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Shadow110
Shadow110
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https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding?redirectlocale=en-US&redirectslug=Firefox+is+already+running+but+is+not+responding

uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86). DO MAC EQUIVALENT Note: your Firefox Profile is saved. But you should make a back up before you do :

Reinstall with Current Release Firefox 57.0.3 with a Full Version Installer

Please let us know if this solved your issue or if need further assistance.