foxfirers33 said

I uninstalled Chrome a week ago because it didn't like "https" I guess. It said I was in danger on may sites.

I'm a little surprised you wouldn't heed that warning. Because this symptom nearly always indicates a "man in the middle" intercepting your browsing. They revealed themselves through this flub.

One thing Facebook and YouTube share is the use of brotli compression. Some intermediaries do not properly handle that and pass through gibberish. That "man in the middle" could be security software, a proxy server, or something nefarious.

To set Firefox to tell sites it only uses older forms of compression, you can try the following:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste enco and pause while the list is filtered

(3) Double-click the network.http.accept-encoding.secure preference to pop up an editing box, and remove this from the end:

<font face="courier new,courier"> , br</font>

so it looks like the line above it

<font face="courier new,courier">gzip, deflate</font>

Then click OK to save the change.

If the site works after that: I think it's important to chase down whatever or whoever is intercepting your browsing requests. (More info to follow.)

One method of investigation is to check a certificate for an HTTPS page and see whether the Issuer information points to an unexpected source, particularly if there is a pattern across sites. For example, on this page, you can view the certificate information through the Page Info dialog. Either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Certificate"
• (menu bar) Tools > Page Info > Security > "View Certificate"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Certificate" button

I've attached what I see for reference. Any differences?

What security software do you have?

There is security software like Avast and Kaspersky and BitDefender and ESET that intercepts secure connections and sends their own certificate or that incorporates special web shielding features that can block content.

Got in to "View Certificate" and my certificate on this this site looked nothing like the one you were kind enough to include. Your "Issued By" was primarily DigiCert on all lines including, Common Name, Organization and Organization Unit. Mine are Lavasoft Limited except on Organization Unit where I had <not part of certificate>. My Certificate Hierarchy was Lavasoft Limited with "support. mozilla.org" and a second line indented. My Extensions were "certificate subject Alt name". I hope this helps because I don't have clue what it means. I know I get the same verbiage on Facebook and YouTube. Thanks for your help

Lavasoft Limited is the maker of the Ad-Aware family of security products. These include:

• Ad-Aware Antivirus
• Ad-Aware Adblock (may be a browser add-on)
• Web Companion (may include a browser add-on)

Do any of those sound familiar?

You can check for whether one or more of these programs is installed using the Windows Control Panel, Uninstall a Program. You can sort by name or install date, whichever you think might be most helpful. Sometimes Web Companion or Adblock might be bundled with some other free software.

With respect to Firefox add-ons: You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then cast a critical eye over the list on the right side. All extensions are optional. If in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

I had Ad-Aware Antivirus on this computer but I thought I uninstalled it. I'll check to make sure. I'll check the others too. I'll let you know what I find. Thanks for the great help!

Well how interesting! I had Web Companion on my computer. I uninstalled that and had it restore my browser to it's original settings. Then I crossed my fingers. Both Facebook and YouTube work now. I don't think the finger crossing had anything to do with it but seriously, do you think now there is no nefarious "man in the middle" or am I safe?

You have been great.

I'm glad that helped, and thank you for persevering through the various dialogs to track it down. Two other people reported the problem earlier this month and didn't stick it out so I don't know what they're doing now.

Unless there are some odd symptoms, I think you're good to go. If you ever want to scan your system for suspicious programs, our support article has links to free tools for that: Troubleshoot Firefox issues caused by malware.