Firefox recently rolled out "Total Cookie Protection" to more users. This limits how sites can use "third party" or "cross-site" cookies, meaning cookies from different websites than the one you see in the address bar. Some sites pass you back and forth between different servers during login because they have their services spread out over a number of different servers. In those cases, you might be able to submit a form successfully on one page and then the next page says you are not logged in. Frustrating!

You can make exceptions to this feature when needed (for each server that you visit as part of the process of using this company's services). More info in the following articles:

• Introducing Total Cookie Protection in Standard Mode
• Total Cookie Protection and website breakage FAQ

Any difference?

@Dropa - All the add ons I use (mostly popup and ad blockers) are the same ones I have always used and have never been an issue previously also none of them have updated or altered recently only the Firefox browser did. I will try disabling them and see if it makes any difference. If so I will go through them one at a time to locate the culprit if any. UPDATE: I disabled them all and it made no difference to the issue in question sadly :(

@Jscher2000 - Sadly turning the Enhance Protection off for the site didn't make any difference unfortunately :(

I hadn't tried in Private mode, but I have now.. also no difference :(

It's difficult to think of a setting other than a cookie setting that could be relevant, but another method to suss out an issue with settings or add-ons is:

New Profile Test

This takes about 3 minutes, plus the time to test your problem site(s).

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 Test2022, 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 Test2022 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 the ISP site 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. (Test2022 will remain available for future testing.)

It's difficult to think of a setting other than a cookie setting that could be relevant, but another method to suss out an issue with settings or add-ons is: New Profile Test Does the ISP site work any better in the new profile?

Done and sadly not, it is still telling me it is an incorrect user name or password. :(

Mark397 said

I hadn't tried in Private mode, but I have now.. also no difference :(

If that is the case if all the Addons are disabled in that mode that would mean your Firefox is corrupted or the installation of the browser was corrupted and this usually means a complete uninstall and reinstall to fix.

Before doing that make sure to backup your data first.

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them https://support.mozilla.org/en-US/kb/password-manager-remember-delete-edit-logins

Only other thing to try is Boot Windows in Safe Mode with Networking and see if the Browser doesn't act differently. As it could be something else outside of the Browser that could be causing this as well. So it's a process of elimination to find the issue at hand.

The Browser is not a recent installation, and out of curiosity if it were a corruption wouldn't that affect more than just a single solitary website log in? It is working fine with every other site and log in.

I'll give the safe boot with networking a go before attempting an uninstall/reinstall of the browser. Is there no fix installation option for Firefox?

UPDATE: There was a little update today to the Firefox Browser when I opened it and now the websiters log in works without issue. So seemingly the Firefox developers have fixed whatever the issue may have been.

Appreciate the attempts at help though folks.