Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

Make sure you are not blocking content.

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}acking-protection-firefox-desktop

Thanks for your reply, unfortunately, your suggested solutions didn't completely solve my problem. I had three sites with the problem, it fixed one of them. For the other two when I attempt to login, entering email and password and clicking sign in, I receive the message "Sorry something went wrong. Please try again." I'm certain the name and password are correct since they work with the Edge browser. I also tried using a private window with no luck. Thank you in advance.

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can remove all data stored in Firefox for a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox for this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data for that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data for that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

Thank you for the additional suggestions. I'm already using the DEFAULT theme. I used the "Forget about this site" but with no change in the error.

What is/are the exact error message(s) ?

I said in my earlier reply, I receive the message "Sorry something went wrong. Please try again." This is coming from the login page. It's like a message "Incorrect username/password" you might receive if you typed the wrong password. I'm certain the name and password are correct since they work with the Edge browser. Thanks for your help

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

Websites don't load - troubleshoot and fix error messages

http://kb.mozillazine.org/Error_loading_websites

What do the security warning codes mean

After working through your list of links, the 5th one lead me to a solution. I followed it to the "fix login issues" article. It lead me to my Kaspersky settings where I disabled "Inject script into web traffic to interact with web pages." Thanks again.

Glad to help. Safe Surfing.