Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

I try to open Firefox. Get error message saying Firefox is already running and needs to close - another error message say Firefox can't open

  • 2 svar
  • 5 har dette problemet
  • 4 views
  • Siste svar av FredMcD

more options

Turned on laptop (rebooted) after being away from it for a few hours. Went to open my home page. Error message popped up saying Firefox is already running and must be closed. I closed it and another error message popped up saying Firefox can't open - incomplete or missing files.

I went into Processes to close Firefox. Selected 'end process' but nothing happened.

Tried to use Internet Explorer but it just gets hung up. Cannot access anything.

And, because I can't open Firefox, I can't go a refresh.

Everything was working just fine a few hours ago.

Any thoughts?

Turned on laptop (rebooted) after being away from it for a few hours. Went to open my home page. Error message popped up saying Firefox is already running and must be closed. I closed it and another error message popped up saying Firefox can't open - incomplete or missing files. I went into Processes to close Firefox. Selected 'end process' but nothing happened. Tried to use Internet Explorer but it just gets hung up. Cannot access anything. And, because I can't open Firefox, I can't go a refresh. Everything was working just fine a few hours ago. Any thoughts?

All Replies (2)

more options

Firefox hangs or is not responding - How to fix

Open the Task Manager and quit the process. If this continues to happen I would recommend starting the PC in Safe Mode with networking.

more options

What is the computer system and Firefox on the bad computer?


Separate Issue; Your System Details on this computer shows;

Multiple versions of your Adobe programs.

Having more than one version of a program may cause issues.

Go to adobe.com and download the full installers after removing all of the old programs.


Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options)
key, and then starting Firefox. Is the problem still there?


This is not a cure but will make it easier if Firefox locks up in Windows. https://support.mozilla.org/questions/997866 {web link}