Are you getting the message from Firefox, or a pop-up?

If you have trouble updating, Download Firefox For All languages And Systems {web link}

In Firefox, I hit "help", then "about Firefox", and it shows version 48.0.1, and "downloading update - 0 bytes of 8.9MB update", but it never progresses or completes. Once, I later saw a pop-up that indicated that it failed....

Updated: about 15 minutes after "launch", I do get a pop-up (apparently from Firefix) that says "Update Failed" and "No data was received, please try again". TaskMgr shows no "spawned" processes, and no network activity during that interval.

The question is why? and how do I/we "fix it"?

And yes, I've read the FAQs, "helpfuls", etc.

And yes, I tried disabling all AV, etc. No help.

Did you try the link I posted for the full program?

Yes, I tried that. Got a "secure connection failed".

What error messages are you getting and what security related software do you use ? See also

• What do the security warning codes mean?
• How to troubleshoot security error codes on secure websites

With XP you will probably need to update fully from within Firefox, or use a full installer

• How can I get the latest version of Firefox on Windows XP or Vista?

FredMcD said

Did you try the link I posted for the full program?

Fred in case you forgot. https://support.mozilla.org/en-US/kb/get-latest-version-firefox-windows-xp-vista

I use AVG Smart Security. As noted, I disabled it, with no change.

Error messages as previously stated.

When I try to download a full copy,of Firefox, the tab shows "connecting", the I get a new tab/page that says "Secure Connection Failed".

FWIW, I went to the NVIDIA site, and executed a download with no difficulties.

I know - appls and pineapples, but... go figger.

Do you even need the Firefox 48.0.2 update?

https://www.mozilla.org/en-US/firefox/48.0.2/releasenotes/ It was made to fix one specific issue. Mitigate a startup crash issue caused by Websense (Windows only) (Bug 1291738)

If Firefox 48.0.1 wasn't crashing for you, you don't need that update.

Plus, I read somewhere that the 'fix' for Websense didn't work and that 48.0.3 was mentioned to provide another 'fix'. And the use of a "hotfix" XPI was also mentioned.

I'm having two current issues:

1) I can't download the current "fix"; whether I need it or not is immaterial.

2) I also can't download Firefox ANYTHING from Mozilla.org...

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?

Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

as stated, running WinXP SP3+ PPOS (still supported)

as suggested, booted to safe mode, ran firefox, selected help/about, and... it worked as it should (eg. downloaded the updates, etc).

Next???

Also, rebooted as normal, and it fails with the "secure connection" screen.

Not sure I can really offer any helpful suggestions at present.

Have you been having problems with other secure sites ? Have you been needing to set exceptions to use secure sites ? What security related software do you use ? You said you can not download anything from Mozilla. What about this support site ? Try for instance to save one of the Avatars from the forum thread . That will necessitate a small download, does that work ?