Here's an answer that has not been shared in the Original Question of the same name. Background: Starting today, I'm receiving an error message with accessing x.com and the x.com thread has been locked. The error message is "Firefox’s Enhanced Tracking Protection (Strict Mode) is known to cause issues on x.com". I've done all of the troubleshooting steps on the original question link and nothing worked. However, @jsher2000 asked a very good question: Can you access a direct link to a user page such as https://x.com/mozilla Well, the answer was no, but I did notice one item: the URL was: https://x.com/?failedScript=vendor, so it looked like x was generating the error. I then turned off NoScript for the tab and nothing. Turned off uBlock Origin and it started working. Turn uBlock Origin back on, it fails again. Disabled and it worked. Turned NoScript back on, no change, still worked. In the end, on uBlock Origin, the site "edgecastcdn.net" was blocked. Enabling that site allowed me to turn uBlock Origin back on.