What is the current setting here?

• Options/Preferences -> Advanced -> Network: Connection -> Settings:

"Do not prompt for authentication if password is saved"

the box is checked.

It's probably a Windows-based server running Microsoft's IIS software and using your network credentials. Is that what it looks like?

Firefox has some extra settings you can set so that you are not prompted every time. I don't know whether these work the same way on Mac but I think it's worth a try.

(0) Select the host name of the server in the address bar and copy it. For example, in

http://intranet/sales/quota.html

the host name is "intranet" (without the quotation marks).

(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 net*auth and pause while the list is filtered

(3) Double-click the network.automatic-ntlm-auth.trusted-uris preference and edit its value as follows:

(A) If this preference is blank, paste the host name you copied and click OK

(B) If this preference is not blank, add a comma at the end, then after that paste the host name you copied and click OK

Test in another tab to see whether that resolves the issue. If not, continue with this next preference:

(4) Double-click the network.negotiate-auth.trusted-uris preference and edit its value as follows:

(A) If this preference is blank, paste the host name you copied and click OK

(B) If this preference is not blank, add a comma at the end, then after that paste the host name you copied and click OK

Any improvement?

Note: In private windows, you'll need to enter your login credentials at least once per session.

Unfortunately I have tried both of those and neither worked. Sorry, to add some more detail, I am on a Mac. And it's not just that the Authentication box pops up sporadically all day, it's that it never actually accepts my user name and password. I click Ok and it just pops right back up.

It's possible that the login is accepted but that you are being prompted for every element of the page (e.g., every style sheet file, every external script, every image).

Does the same login work in Safari?

Could you try copying a URL to a single item (e.g., one image) to Firefox and see whether you can open that successfully.

If that doesn't work, I suggest checking with your IT on whether there is a known issue with Firefox/Mac.

The same login works in Safari and Chrome.

Unfortunately the single item link did not work either.

Firefox also works for every other user we've tested, just not me :(.

Tried reinstalling, clearing cache, clearing keychain - no luck! Tried testing older versions of Firefox - no luck!

Could you test in a fresh Firefox profile:

New Profile Test

This takes about 5 minutes, plus the time to test the site.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the Create a New Profile button, then click Next. Assign a name like July2017, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but I think those are still "under construction" so please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new. If you are prompted to approve extensions, just ignore/close those tabs for the time being.

Does your intranet page work any better in the new profile?

If it does, try quitting Firefox and starting it back up again to trigger multiprocess mode. Then test the intranet again; still working?

When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.