Try these two steps.:

Clearing Cache

1. Press 'CTRL/CMD + SHIFT + DEL
2. Select "time range to clear" to Everything
3. Expand the "Details" by clicking the Arrow
4. Uncheck everything except Cache
5. Click Clear Now

Go to your Profile Folder (Help > Troubleshooting Information > Profile Directory > Show Folder)
Delete all sessionrestore.js files and restart Firefox.

Clearing Cookies

1. Go to the orange Firefox button > Options > Privacy > Remove individual cookies
2. Search for the site you are having issues with (reuters.com) and click Remove Cookies
3. Restart Firefox and try again

Thanks,

Had tried both steps before, with no success. Now, I tried Go to your Profile Folder (Help > Troubleshooting Information > Profile Directory > Show Folder) Delete all sessionrestore.js files and restart Firefox

Did not see any sessionrestore.js files, but there was a sessionstore.js file which I deleted. Even then, the website does not load.

Can you try to start Firefox in Safe Mode to see if Firefox works properly with no error? You can start Firefox in Safe Mode below:

• Windows/Mac: Go to Help > Restart with add-ons disabled
• Linux: Run firefox -safe-mode in the Terminal/Konsole

If Firefox opens up fine with no problems, it's probably one of your extensions that's causing the issue. You can re-enable your add-ons one by one until you find the one that causes the issue upon being re-enabled.

Hello again, thanks for your help. Https-Everywhwere is the Add-on that creates the problem with reuters.com; now I have temporarily exempted that website from the Add-on, and everything seems to work.

Sweet, glad you got that working!