With unexpected blank pages, the first thing I always suggest is to make sure the redirect block didn't get turned on. Here's how to check that:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future. Since we are restoring the default value, I feel comfortable mentioning it.

(2) In the search box in the page, type or paste accessibility.blockautorefresh and pause while the list is filtered

(3) If the preference has a value of true, double-click it to restore the default value of false

Otherwise, could you test in Firefox's Troubleshoot Mode? In that mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is running:

You can restart Firefox in Troubleshoot Mode using either:

• "3-bar" menu button > Help > Troubleshoot Mode...
• (menu bar) Help menu > Troubleshoot Mode...

and OK the restart. A small dialog should appear. Click the Open button.

If Firefox is not running:

Hold down the option/alt key when starting Firefox. A small dialog should appear. Click the Open button.

Note: Don't use the Refresh without first reviewing this article to understand what will be deleted: Refresh Firefox - reset add-ons and settings.

Any improvement?

Ref. Diagnose Firefox issues using Troubleshoot Mode

If you use the MetaMask extension, other users are reporting that it breaks a lot of pages:

• https://support.mozilla.org/questions/1500324
• https://old.reddit.com/r/firefox/comments/1jevp4r/psa_disable_the_metamask_addon_if_you_have_it_and/

The MetaMask extension authors have a version 12.12.1 update as you can see at https://addons.mozilla.org/firefox/addon/ether-metamask/versions/

Thank you Jefferson and James - I think it was MetaMask. I was busy in work this week so went on this weekend to sort it out and found it was working again - and MetaMask had been updated to 12.12.1. Seems as if that resolved the problem. Anyway, thanks for helping out. All the best. David