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When closing browser I get this message: Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window.

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  • 1 has this problem
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  • Last reply by FredMcD

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For last 2 years I get following message after previously closing Firefox browser and later in same computer session after clicking on Firefox icon to initiate new browser:

Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window.

I have updated Firefox every time new version is available and still same issue over last 2 years.

For last 2 years I get following message after previously closing Firefox browser and later in same computer session after clicking on Firefox icon to initiate new browser: Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window. I have updated Firefox every time new version is available and still same issue over last 2 years.

All Replies (3)

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Make sure you close the browser using; Windows: Menu > File > Exit Mac: Menu > Firefox > Quit Firefox Linux: Menu > File > Quit

Some users have reported issues when closing the browser using the X upper-right of the window.


https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding

https://www.basezap.com/cant-open-firefox-because-a-copy-of-firefox-is-already-open-mac/

https://apple.stackexchange.com/questions/196771/cant-open-firefox-because-a-copy-of-firefox-is-already-open

http://kb.mozillazine.org/Firefox.exe_always_open

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Thanks but I already know this. Want to close browser by clicking "X" at upper right like every other browser.

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As my last post says; Some users have reported issues when closing the browser using the X upper-right of the window.

When you start Firefox, it creates several sub-programs. The reason for this is; if one process should lock up or whatever, the user can still have some control.

More than one process is normal for the current Firefox. http://www.ghacks.net/2016/07/22/multi-process-firefox/

Multi-process Firefox is codenamed "e10s". https://wiki.mozilla.org/Firefox/multiprocess