We're sorry to hear that your Firefox seems to be crashing when you open it. Please perform the following steps to give us a crash report ID that helps us find out more about the cause of the crash.

1. On the keyboard, press [Windows] The image "Windows key" does not exist. + [R]. This should bring up a Run window that contains a text field.
2. In that text field, type %APPDATA% and press Enter. An explorer window should open.
3. From that explorer window, double-click on the Mozilla folder, then double-click on Firefox and then on Crash reports. Double-click on submitted.
4. Now, you should see a list of files that contain reports. Go to View > Arrange Icons by > Modified to get the most recent files at the top of the window.
5. Open the most recent 5 files with a text editor and copy the IDs.
6. Paste each ID with bp- into the reply window on the forums.

Thanks in advance!

You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

If you have not tried shutting down and restarting Windows since this problem started, I would try that next.

If you are not getting any kind of crash dialog, either from Windows or from Firefox (Mozilla Crash Reporter), Windows may be "killing" Firefox early in the startup for some reason. Perhaps...

A Recent Issue for 64-bit Windows Users with 64-bit Firefox

One of the main effects of the Firefox 56.0.1 update was to switch 64-bit Windows users from the traditional 32-bit version of Firefox to the 64-bit version. We've received a number of puzzling reports of Firefox either not starting (probably due to incompatibilities with 64-bit drivers that Firefox expects/requires) or not loading any pages after this migration.

One user discovered that Windows was silently killing Firefox at startup and recording it in the Windows event logs (you can view event logs using the Event Viewer). Based on one of the reports in the log, we were able to trace that to an out-of-date Logitech camera driver, of all things. Four other users reported that uninstalling the Logitech camera resolved their problem as well.

• https://support.mozilla.org/questions/1179822#answer-1019375
• https://support.mozilla.org/questions/1181740#answer-1021470
• https://support.mozilla.org/questions/1181405#answer-1022798
• https://support.mozilla.org/questions/1182572#answer-1023413
• https://support.mozilla.org/questions/1182847#answer-1024290

Do you want some assistance in looking at event logs, or do you have such a camera?

If the investigation doesn't yield any solutions, it is worth trying a return to 32-bit Firefox.

While normally this kind of change is seamless -- the installer detects your existing data and preserves everything -- you might want to make a backup "just in case."

• Back up and restore information in Firefox profiles
• How to opt out of 32-bit Firefox migration to 64-bit

Note: If you decide to try 64-bit Firefox on the same system at some point in the future, see: How to switch from 32-bit to 64-bit Firefox.