How to get rid of "Access Denied" messages.

Dell indeed uses Akamai/Edgesuite.

There are addons that might make the navigations look suspicious but given you specifically mention this also happening in troubleshoot mode that has all the extensions disabled, this could point to a miscalculated block unless your IP address has bad score for some reason.

If you can also verify using a temporary new profile, and eventually downloading Nightly for a separate test, the next course of action would be either uploading screenshots of few of the blocks, or directly filing the reports per site in bugzilla quoting the reference IDs returned on the 403 blocks so that complaints are submitted for these. Thanks!

I created a new profile and had no problems; should I copy the stuff from my old profile to the new, or rebuild the profile from scratch?

jbr is likely to answer.

Personally I would start from scratch.

and copy over parts of the old profile, keeping backups of the new one. You may discover where the problem lies and have an idea on how to avoid any similar problems

What is loaded in troubleshooting mode, but is not in new profiles, is mainly session data.

Might be worth trying to either "Clear cookies and site data" from the shield icon next to the address bar for the malfunctioning sites, or selectively remove the data for the domains affecting your from the site data management pane, see: https://support.mozilla.org/en-US/questions/1588761#answer-1827079

jbr, I created a new profile from scratch. I also cleared the cookies and such for dell.com. I'm still getting the problem. What do I try next? ?": (Note: FWIW, it works on Chrome.)

"I created a new profile and had no problems; "

" I created a new profile from scratch. I also cleared the cookies and such for dell.com. I'm still getting the problem."

So when did it happen again?

This is somewhat tricky. If it didn't work in fresh profile, there would be ways to escalate — but seeing the different behavior between profiles might mean it's something trivial, e.g. old settings–related (like, changing config for media playback, webgpu, webrtc, anything tinkered with while improving something seemingly unrelated months or even years ago) ~ which now the bot protections deem as trying to tamper with their evaluation:(

Might be something like a protocol or cipher suite disabled in the past that now stands out etc. …

Do you use any VPN by the way? Or have e.g. Malwarebytes scan your secure connections?

I have the default Firefox VPN (the free one).. I'[ll give it a try. Also, I had some other problems, so I refreshed Firefox and the other problems went away--but not this one.