Hi Joey, you seem to specialize in difficult questions. ;-)

In the Firefox source code, there are two possible reasons for the message that seem quite different:

     case NS_ERROR_CORRUPTED_CONTENT:
       // Broken Content Detected. e.g. Content-MD5 check failure.
       error = "corruptedContentErrorv2";
       break;
     case NS_ERROR_INTERCEPTION_FAILED:
       // ServiceWorker intercepted request, but something went wrong.
       error = "corruptedContentErrorv2";
       break;

I don't know whether Firefox's Web Console (Ctrl+Shift+K) shows anything specific to distinguish between the two cases?

At one point, this error occurred on Twitter if the user had set Tracking Protection to Strict. The workaround was to Unregister the service worker Twitter had previously installed for push notifications (Twitter isn't working on Firefox). Or possibly turning off Tracking Protection on the site?

Is it the kind of site where you feel comfortable disabling Tracking Protection? To do that, click the shield icon at the left end of the address bar and then click the slider switch at the top of the drop-down to disable protection. Firefox should reload the page. It's possible you might also need to Unregister a service worker and let the site install it again so there is a fresh connection attempt.

I'm not sure what happened the last week! :-)

Regarding the steps to try:

1. I checked the Web Console and the message was: "No strings exist for error: corruptedContentErrorv2"

2. I checked about:serviceworkers as the Twitter thread says, and it says "No Service Workers registered."

3. I use standard tracking protection.

I also deleted all the data/cookies (sad face) even though the issue impacted the private browsing too. Still not fixed.

My biggest issue currently is the slow YouTube loading (many reports on Reddit and a few here). The videos load fine, it's the icons on the website, etc.

I'm thinking it's time for a complete uninstall (been many years!), delete profile but keep history, passwords, etc., and see. But that's too drastic.

Well, hmm. Not really enough information to know what is causing it. There certainly could be some kind of site compatibility issue. To report the URL, if you want to do that, you can use either

• menu button > Report broken site
• (menu bar) Help > Report broken site

More generally, before undertaking drastic measures, how about:

New Profile Test

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Take a quick glance at the page and make a mental note of which Profile has this notation: This is the profile in use and it cannot be deleted. That is your current default profile.

Click the "Create a New Profile" button, then click Next. Assign a name like TubeTest, ignore the option to relocate the profile folder, and click the Finish button.

Firefox will switch your default profile to the new one, so click the Set as Default Profile button for your regular one to avoid an unwanted surprise at your next startup.

Scroll down to TubeTest and click its Launch profile in new browser button.

Firefox should open a new window that looks like a brand new, uncustomized installation. (Your existing Firefox window(s) should not be affected.) Please ignore any tabs enticing you to connect to a Sync account or to activate extensions found on your system to get a clean test.

Does YouTube work any better in the new profile?

When you are done with the experiment, you can close the extra window without affecting your regular Firefox profile. (TubeTest will remain available for future testing.)