G3 3579, BIOS fails due to password

Have you tried either of the alternative methods to update BIOS, outside Windows, that are listed under Installation instructions on the page where the latest BIOS is offered.

Using a bootable USB stick seems to be the simplest way. You can create a bootable USB using Rufus (free). After you run Rufus, copy the BIOS .exe file onto that stick. 

With PC powered completely off, plug the bootable USB into PC and power on.
Notes:
You can't just do a Restart from inside Windows
Keep PC plugged into its charger

When you see the Dell splash screen, tap F12 to open the menu and choose the option to boot from USB. Launch the BIOS .exe from the USB by typing in the exact file name and pressing Enter.

Just leave PC alone while the update is working. PC may reboot several times. Even if it looks like PC shut off and isn't doing anything, just leave it alone until you're safely back at the desktop.

Thank you @RoHe for explaining this alternative method. No, I haven't tried it.
I'll keep it in mind, but I'd rather wait until a newer BIOS version is released, just in case the latest package is having some issues. It isn't worth the risk of updating to a potentially problematic version.

You never mentioned what version of BIOS is installed now...

The password error when updating BIOS seems to have affected several different PC models. Users who used the USB method have gotten their update to install even though it wouldn't install inside Windows.

The latest BIOS update fixes a number of security issues, so if you're comfortable not having those patches, it's probably ok to wait for the next version. And hopefully this is resolved before the next update is released for your PC model, whenever that might be...

I currently have version 1.22.0 (August 2022) installed, and my device runs Windows 10 22H2. I was trying to update to version 1.23.0 which is the latest BIOS available for my device at the moment. I have been always updating the BIOS through Dell Update with no issues, however a couple of times Windows Update detected and installed a new BIOS version automatically before I initiate it myself. I honestly hate it when Windows automatically updates the BIOS for me because I need to ensure I got everything backed up first. I don't appreciate surprises with such critical system updates. Any idea on how to stop Windows from automatically updating the BIOS? I tried turning off “Device installation settings” from Advanced System Settings in Windows 10 but it kept installing drivers and firmware updates anyway.

Open BIOS setup and look for a UEFI Capsule Updates option. Disabling that is supposed to prevent Windows Update from installing BIOS updates, assuming this option is available on this PC model. 

If you have Win 10 Pro, there's Group Policy setting that can be changed to prevent all driver and BIOS updates, but that might not be a good idea especially because Intel offers important driver updates via Windows Update.

Keep in mind that every BIOS update will re-enable UEFI Capsule Updates, regardless of how the BIOS update is installed, so you'll have to stay on this each time you update BIOS...

Disabling that option won't prevent Dell Update or SupportAssist from doing updates automatically. So you'd have to disable or uninstall those apps from your PC.

And that means you'll have to search for new Dell updates manually by entering your Service Tag on the Support page. (Don't post it here!) Then manually download the latest ones you want/need onto your PC and double-click each one to install it.

Thanks a lot for sharing these tips. I will do a little more research first before making any changes to make sure I fully understand how this solution may affect my experience. For the record, I have Windows 10 Home, so the second option (Group Policy) won't be applicable for my device anyway.

I hope a new BIOS version gets released soon for my device with a fix enabling it to be installed normally through Dell Update like it used to be.

The question is when will the next update be released?

I pinged forum moderators about this thread to they can pass the info along. I haven't seen any other posts about this issue on a G3 3579 with BIOS 1.23.0, so it's possible it's something with your specific PC. And unless the tech team can repeat the error, they won't be able to fix it...

I understand. However, I have seen multiple threads (posted over the past week) reporting the same exact issue for other models. Is it possible that there is a shared issue affecting recent BIOS updates for multiple models? For the record, Dell Update client received a recent update in the past few days. Could it possibly be that the issue is caused by Dell Update itself rather than a faulty BIOS package?

Version 1.23.0 has been released for my device on OCT 26, so I guess it's still early to tell if it's an issue affecting this device model or if it's only unique to my unit. Perhaps not enough users have attempted to update to the latest version on this particular model yet. I'll just wait and see if any new reports surface up.

Users who attempted to install a recent BIOS update manually in Windows, without using Dell Update or SupportAssist, have had similar problems   So it might be the packaging around the actual BIOS updates or possibly even some recent Windows update.  So just stay with the BIOS version you have now and see what happens...

Are you logged into an account with Admin privileges when you get the request for a password?  What level do you have the Windows User Account Control (UAC) setting at? Perhaps disabling UAC right before trying to install the BIOS update would avoid the problem. Don't forget to reset UAC to the level you want afterwards, successful BIOS update or not...

Out of curiosity, are you using Windows Defender (Windows Security) or some other anti-malware app (eg McAfee, Norton...)?  Maybe one of them is blocking BIOS updates and asking for a password as security protection.

We're pinging our Dell contacts with links to threads reporting these problems, so it's up to them to sort it out...

It's a personal PC and I'm the only user and administrator, so I believe my account should have all the necessary admin privileges for installing firmware updates. I do have Windows Security installed by default, but it generally never caused any issues. Still, it might be a Windows-related issue like you suggested, whether caused by a recent update or something else.

That's the plan, I'm going to stick with the current BIOS unchanged and wait for a newer version.

Thanks a lot for your time and effort to follow up and get in touch with Dell regarding this issue.

You're welcome. 

Hopefully Dell will fix this soon, since it's happening with BIOS updates on lots of different PC models...

Thanks a lot @DELL-Chris M for the notice and the recommendation you provided.

I have two simple questions: 
1. Does the USB flash drive need to be bootable in order to follow that method?
2. Does updating the BIOS using a Flash drive render the USB stick unusable afterwards, or can I re-format it and use it normally after completing the update process?

1. Does the USB flash drive need to be bootable in order to follow that method?
* Nope. The instructions state that you are simply formatting it to FAT32.

2. Does updating the BIOS using a Flash drive render the USB stick unusable afterwards, or can I re-format it and use it normally after completing the update process?
* Sure. But why not save it as is for future BIOS updates? Then all you have to do is save the new BIOS to it.