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!

Avatar for Username

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

This thread was archived. Please ask a new question if you need help.

Firefox thinks it's already open and won't let me open it.

smarzen
smarzen
more options

Firefox quit uncleanly. When I try to open it now, I get the error message:

Close Firefox

A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Firefox quit uncleanly. When I try to open it now, I get the error message: Close Firefox A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

All Replies (1)

Wesley Branton
Wesley Branton
more options

You can use the task manager to end any open Firefox processes. There are likely some open still, even if the Firefox window is not visible.

If you aren't able to do this, simply rebooting your computer should fix the issue because that will close any Firefox processes.