hi, are you using any extraordinary security setup (sandboxie, or other tools/settings that are not commonly in use) and do you see any entries related to firefox in the applications section of the windows event viewer when you launch the browser?

Hi, no security tool is installed and unfortunately no entries in event viewer in the application section as in system section as well.

Hi, this is often caused by a security program or anti-virus which may need updating. To test, disable your AV (you have already confirmed that you don't have any other security programs) and see if Firefox is OK.

Also work through Firefox can't load websites but other browsers can.

Just to confirm that Run this program in compatibility mode for: must be deselected.

If you use userChrome.css - you don't have it if you don't know what it is, this is also an unlikely but possible suspect, and can be disabled to test by placing /* before, and */ after the file in the chrome folder, then restarting Firefox.

could you test if the issue is fixed in today's nightly test builds?: https://www.mozilla.org/firefox/all/#product-desktop-nightly

I've had a similar problem after updating to Firefox 70 on my Windows 7. It only works if I boot Windows 7 in Safe Mode. If I boot it in Normal Mode none of the pages load except for when I click Help->Troubleshooting Information. And in my case downgrading Firefox back to versions 60s and even 50s didn't help at all.

@Scribe: I disabled the AV program but no luck. alos, I confirm that Run this program in combatibility mode is unchecked. I don;t know what userChrome.css is but I checked it now and it not present.

@philipp: Yes, the nightly version worked! Should I remain with this version, waiting for a working update?

Nightly 75.0B1 works for me!

I think there is a minor update planned for Firefox 73 next week to comes with a fix, so keep an eye on that. Note that you should use Nightly build with a separate profile (Nightly might do that automatically) because otherwise you will corrupt your current profile for release.

See also:

• Bug 1614885 - Firefox 73 no longer able to load content when launched in Win7 compatibility mode

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

Thanks @cor-el and @phillipp for all your updates and overall support! Looking forward for the fix.

Firefox 73.0.1 containing the patch got released now: https://www.mozilla.org/firefox/all/#product-desktop-release

philipp said

Firefox 73.0.1 containing the patch got released now: https://www.mozilla.org/firefox/all/#product-desktop-release

Thank you philipp! Patch 73.0.1 fixed the issue for me!