Certain websites may detect Enhanced Tracking Protection as an ad blocker. If Enhanced Tracking Protection is preventing a specific website from not working properly, you may need to disable it on that website.

See Enhanced Tracking Protection in Firefox for desktop for more information.

Hope this helps.

I do disable enhanced tracking protection when this happens, and much of the time it works, but not always. About a third of the sites continue to be unavailable, so there has to be something else going on.

In what way are websites not accessible ?

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows an highlighted shield icon at the left end of the location/address bar in case Tracking Protection is blocking content.

• click the shield icon for more details and possibly disable the protection

You can check the Web Console about what content is blocked

• "3-bar" menu button or Tools -> Web Developer
• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" for websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Manage Data

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

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

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

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

Thanks for the suggestions. I tried them all but nothing changed. The site stays grayed out with the ad blocker pop-up coming back after every attempt. There are no add-ons that have anything to do with privacy or security. I get the same result in safe mode, and hardware acceleration is already turned off.

I should mention that I get no similar results using Edge (not the chromium-based beta) with similar settings, and with the tracker-blocking browser, Epic.

Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

• https://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• https://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

Also make sure your router isn't blocking content.

No network issues, and I the affected pages load just fine in every other browser I tried. Thanks for helping.

I have the exact same issue and none of these suggestions worked. In my particular case the website was the washington post, disabling the shield, clearing the cache, restarting the browser all didn't work.

WaPo is still unattainable, but I solved all the other issues by removing and reinstalling the program.