Rather than uninstall/reinstall, you might want to delete the cache and cache2 folders and let Firefox create new ones. I have a reasonable idea of how to do that on Windows but because there are differences with various things on Mac, I am not confident recommending how to do that on your system.

You're a prince, jscher2000, to have spent this time with us on the problem. I have no confidence, at all, in my ability to delete the cache folders safely. It certainly sounds like an eminently reasonable and wise thing to try, but I don't think I'll attempt it.

Perhaps, I'm just being overly paranoid, but it doesn't seem right, at the very least, that for years clearing the cache meant actually clearing the cache, and now it doesn't. I don't like being tracked or snooped upon, and that's all I am really worried about. Also, what little logic upon which my brain operates is offended at this anomaly, if that's what it is.

It seems too trifling an issue to haul the thing off to a Genius appointment at the Apple store. I don't know. Thanks, again.

jscher2000 said

Does that same error show up other times that you use the Clear Now button?

Don't know what "same error" you're referring to, nor would I know, since I've only done the "open browser console" this one time, so I don't know if the same errors keep coming up. What if they did, what could I do in that case?

StevenCee said

Don't know what "same error" you're referring to, nor would I know, since I've only done the "open browser console" this one time, so I don't know if the same errors keep coming up. What if they did, what could I do in that case?

This one that you reported several posts up:

TypeError: Type does not implements method: modelFor#1dv52p6m9co core.js:116:1

(https://support.mozilla.org/questions/1115465?page=1#answer-859680)

I don't see an obvious connection between that error and clearing the cache, as I reported in: https://support.mozilla.org/questions/1115465?page=1#answer-860009

Therefore, watching for it during future cache clearing could help in assessing whether it is worth spending more time investigating or whether it was a coincidence.

Well, gentlemen, suddenly I have this problem no longer. The other evening as I was shutting down Firefox, following a good browsing of the Internet, Firefox continued active for quite some time, not completely disengaging though the window closed. After a long while, wishing to turn the computer off, I "force quit" the application, and shut down. Since that night, I am able to clear the browser cache completely, whenever I choose. The 437Kb have "gone away", and I have no idea why. Thank you, both, for the conversation and assistance.

Thank you for the update.

When Firefox "crashes" (whether it trips and fall on its own or you force quit), it invalidates the existing cache to avoid using possibly corrupted files. Not what I would recommend as a solution, but...

jscher2000 said

Rather than uninstall/reinstall, you might want to delete the cache and cache2 folders and let Firefox create new ones. I have a reasonable idea of how to do that on Windows but because there are differences with various things on Mac, I am not confident recommending how to do that on your system.

Where are the cache folders? I've looked and searched, and can't find them.