We're sorry to hear that Firefox is crashing. In order to assist you better, please follow the steps below to provide us crash IDs to help us learn more about your crash.

The crash report is several pages of data. We need the report numbers to see the whole report.

1. Enter about:crashes in the Firefox address bar and press Enter. A Submitted Crash Reports list will appear, similar to the one shown below.
2. Copy the 5 most recent Report IDs that start with bp- and then go back to your forum question and paste those IDs into the "Post a Reply" box.

Note: If a recent Report ID does not start with bp- click on it to submit the report.

(Please don't take a screenshot of your crashes, just copy and paste the IDs. The below image is just an example of what your Firefox screen should look like.)

Thank you for your help!

More information and further troubleshooting steps can be found in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

About how long before the browser freezes? What is on the pages at the time? Flash?

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Seburo, No crash reports in the last 4 month.

FredMcD : It varies how long it will last before crashing. It can take hours or an entire day. My desktop did once today and my laptop did it getting to this page. It usually happens when I click the + to add a new tab. It just freezes up, the mouse is movable for about 20 seconds, then it freezes up. Then there is nothing to be done. Ctrl, Alt, Delete does not work at any point after firefox goes into "not responding". No Flash has been running during any of these crashes. (also of note one computer is brand new). I will try starting in safe mode and see if that lasts.

How to crash Firefox (All Systems); Instructions here; https://developer.mozilla.org/en-US/docs/Mozilla/How_to_report_a_hung_Firefox

This page has instructions and a program that can crash Firefox. The next time Firefox starts to freeze, use this.

When multi-process windows in Firefox is enabled then Firefox will use more memory and may be less responsive. Try to disable multi-process windows in Firefox to see if that has effect.

You can disable multi-process windows in Firefox by setting these prefs to false on the about:config page.

• browser.tabs.remote.autostart = false
• browser.tabs.remote.autostart.2 = false

• http://www.ghacks.net/2016/07/22/multi-process-firefox/

I started having this problem a couple weeks ago, too. Especially accessing Microsoft Outlook 365 website. Firefox 52.0 and later 53.0 would say Not responding, and the whole laptop would lock up. I needed to do hard powerdown reboot to recover. I traced the issue to Microsoft .NET 4.5.1. I uninstalled .NET 4.5.1 and all of its updates, and I have no more lock ups.

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

Of course removing .NET 4.5.1 only works if you are not using some application that depends on it. Fortunately, I knew I no longer needed it. Maybe Microsoft or Mozilla can figure out a root cause and release a fix.

It was very disconcerting as I haven't had a hard lockup for many years until this started happening a few weeks ago. It happened about once every day for a couple weeks, usually starting a new tab to open Outlook 365 website.

I could not do the crash report thingy because of the hard lock up. Exact same symptoms as seal7razor, mouse could move for maybe 20 seconds, no ctrl-alt-delete, no alt-tab, nothing,, complete lockup.

Sorry to say that I just had another lock up. After lockups every day for 2 or 3 weeks,, I had backed out .NET 4.5.1 that was installed about the time I thought lockups started. No lockups for 1 week, then I had a lockup today.

In all of the lockups, it seems to be the first time using FF after resuming from hibernate. In the previous cases, it was always when opening a new tab by clicking on the +, then clicking on my ms outlook 365 thumbnail on the FF startup page. This time, I did not click the new tab + as I was already on a blank startup page. I only clicked on the outlook 365 thumbnail. Using WIndows 7 Professional x64 HP pavilion

Same problem. Hit the + and message says "Firefox not responding". It happens once a day or a little less. Enter Control Alt Delete and whole computer completely locks up. Have to do hard reboot. NO crash report! I re-installed Firefox but I don't have much hope for that . I probably didn't do it right because after installing Firefox, when I opened it the same tabs opened that were on it when it locked up. Update: Opened new tab and Firefox froze then locked up computer. Mouse worked for about a minute then everything quit. I had only been using it for less than an hour and was opening a 4th tab. No crash report in Firefox and Windows just shows that it shut down improperly. Next I'll try removing all Firefox folders when I re-install. This is getting very frustrating. One more crash and I'll switch to Explorer until a fix comes out.