That is strange. It usually means that the protocol of the address is unusual, and not http: or https: which Firefox knows perfectly well how to handle.

Could you check whether this is a problem with Cloudflare, which is the default "DNS over HTTPS" service in Firefox? This article describes how to change the setting: Firefox DNS over HTTPS.

Thanks for your help. I tried all of those you suggested and still had the problem. I refreshed Firefox in safe mode and didn't have the problem. It ended up being one (or more) of my extensions. I went through process of elimination and deleted quite a few of them until I didn't have the problem. Fortunately I was able to keep the extensions I use routinely. For now, that solved the problem.

Are you specifying the protocol?

• https://www.wsj.com/

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Reboot the computer into Windows Safe Mode with network support to see if that has effect.

• https://www.bleepingcomputer.com/tuto.../how-to-start-windows-in-safe-mode/
• https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/