What are the exact error messages?

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

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

I've tried opening Firefox in safe mode, but the problem still persists :(

Logging in to my NatWest bank account for example, I can see all my account details, download statements etc., but as soon as I try to perform any transactions or move funds, I get the attached page showing. The service is not "temporarily unavailable" as indicated, since I can log in and transfer funds using Chrome or the mobile banking app without problem.

If I try to log in to my account at https://www.myargoscard.co.uk, again I can log in OK, but the moment I click on the "View my account" link, I'm logged out again. This process continues in a circle each time I try, but again, if I log in using Chrome, I can access the account without problem.

These are only Firefox Quantum issues, they never occurred with earlier versions of Firefox, and don't occur with other browsers.

One issue that seems more common lately is Firefox's Tracking Protection feature. When it is blocking content in a page, a shield icon will appear at the left end of the address bar next to the padlock icon. This article has more info on managing this feature: Tracking Protection {web link}

Thanks for the additional information, but no, that's not the problem.

I've now found that Quantum is flatly refusing to allow me to log in to my Instagram account, regardless of whether I use private browsing or safe mode :(

In view of these issues, and the fact that I can no longer use my favourite, and most useful, add-ons, I'm going to remove Quantum and reinstall an older version of Firefox.

First, Type about:preferences#advanced<enter> in the address bar. Under Advanced, Select Update.

[v56+] Type about:preferences#general<enter> in the address bar. Select Update.

Select Never Check For Updates.

Also turn off Use a background service to install updates <Windows Only>

Install Older Version Of Firefox {web link} Be sure to read everything here.

If you still want to downgrade, look under; I still want to downgrade. Click the Directory of other versions and languages link. Look for the directory of the version that you want. But, remember that old versions may have security issues.

You should also check out Firefox; Extended Support Release {web link} ESR Notes System Requirements

I have tried the aforementioned changes to the options including disabling automatic updates to FF 59 and its add ons. But every time I reinstall 58 it is only good for the one session. As soon as I quit the program, it automatically updates to 59 again!

I need this to stop. It is taking up far too much of my time. How do I make sure that 58 remains the only version on my PC until I actually want to update?

BTW, it appears that FF has installed itself in two areas of my PC: Program Files and Program Files (86). I think this may be the issue. How do I make sure that there is only one version of FF on my PC and that all my user information is retained?

@ SubMariner :

This thread has already been marked as solved - you'll stand a better chance of getting answers if you'll start a new thread.

You can click on the 'Ask a Question' at the top of this page and post your question.

Hi SubMariner

The version in Program Files is a 64-bit Firefox version and the version in Program Files (86) is a 32-bit Firefox version. Firefox wouldn't switch from one to the other in normal cases, but you can be switched to a 64-bit version if you currently have a 32-bit Firefox 58 version.

• https://support.mozilla.org/en-US/kb/switch-32-bit-64-bit
• https://support.mozilla.org/en-US/kb/how-do-i-tell-if-32-bit-or-64-bit