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

Lolu chungechunge lwabekwa kunqolobane. Uyacelwa ubuze umbuzo omusha uma udinga usizo.

Firefox crashes

  • 3 uphendule
  • 1 inale nkinga
  • Igcine ukuphendulwa ngu jscher2000

more options


Firefox worked great until yesterday when I migrated a bunch of files from my old computer...a computer that was operating Windows XP. My new PC (the one where Firefox is constantly crashing) is operating Windows 10.

Firefox crashes when: I try to download a photo I try to download a video I try to change the download folder location

Also, I noticed that Netflix videos will no longer play. It looks like they are just constantly loading. (red spinning circle in the middle). You Tube seems to work alright.

Photos and videos download just fine in IE. I am not extremely computer literate, so I could use as much help as possible.

All Replies (3)

more options

Hmm, what did you migrate? Firefox wouldn't normally be affected by folders like Desktop, Documents, Downloads, but mixing Firefox's data files between different setups could cause issues. If you installed any programs that weren't installed before, that might also be a factor.

Do you have any crash report IDs? That one was incomplete (missing technical details about what Firefox was doing at the time of the crash).

more options


Thank you for your reply. Try this crash report.

I used the program PC mover that came from Dell with my new PC. I honestly don't know exactly what it migrated. I assumed it would just move personal files, and nothing program related.

more options

Maybe that program keeps a log of what it does?

Your Firefox reported itself to the forum with this "user agent" string:

User Agent: Mozilla/5.0 (Windows NT 5.0; WOW64; rv:48.0) Gecko/20100101 Firefox/48.0

Could you reset an internal preference and see whether that goes away?

This article has the steps to clear it: How to reset the default user agent on Firefox.

Then you can view the current user agent string on my test page here (it's in red text) to confirm it shows Windows NT 10.0 now:

If it doesn't show Windows 10, we can suggest how to make sure Firefox is not running in backwards compatibility mode for whatever Windows NT 5.0 was (possibly Windows 2000?).

Your crash report "modules" list mentions filesyncshell.dll, which seems to be associated with Microsoft One Drive, and ClientTelemetry.dll which may be associated with rFactor. I'm not sure if those are significant references, but they are somewhat unusual in my limited reading of crash reports.

Were you opening a file from or saving a file to or listing files in OneDrive around the time of the crash?

Perhaps as a general reality check, you might:

(1) Use the Windows 10 "System File Checker" to make sure all is well and nothing new got replaced by something older: - in Step 1, the instructions for Windows 10 are just below the purple Windows 8.1 screen shot

(2) Check for Windows updates using the Control Panel:

(3) Reinstall Firefox without removing your existing data

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

It only takes a few minutes.

(A) Download a fresh installer for Firefox 48.0 from to a convenient location. (Scroll down to your preferred language.) For maximum plugin compatibility, choose the "Windows" version (32-bit) rather than the 64-bit version.

(B) Exit out of Firefox (if applicable).

(C) Using Windows Explorer/My Computer, rename the program folder as follows:

C:\Program Files (x86)\Mozilla Firefox


C:\Program Files (x86)\OldFirefox

(D) Run the installer you downloaded in step (A). It should automatically connect to your existing settings.

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

  • \OldFirefox\Plugins
  • \OldFirefox\browser\plugins

Any improvement?