BIOS Update blocked due to unsupported downgrade

Question

In may 2022 I updated BIOS on my Optiplex 5055 Ryzen APU company desktops from version 1.2.50 to 1.5.0. Version 1.5.0 is no longer available for download, as You can see here https://www.dell.com/support/home/cs-cz/drivers/driversdetails?driverid=hfvxf&oscode=wt64a&productcode=optiplex-5055-r-desktop , which is strange because at that time it definitely was and I still have that file. The problem is, when I want to update to newer versions (1.6.1 and later)

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I got the message "BIOS Update blocked due to unsupported downgrade". I got this same message even if I want to downgrade BIOS to previous versions.

DELL-Nat M · Answer

A BIOS update is not always blocked from downgrading. However, certain BIOS versions contain security fixes that prevent the system from being vulnerable to threats. These BIOS versions cannot be downgraded due to security considerations. Additionally, we do not recommend downgrading the BIOS unless it is absolutely essential.

If you have more questions regarding your BIOS, please contact our technical support team for individualized assistance based on your specific model and BIOS version. You can reach them using the Get Help Now chat feature located at the bottom right corner of the page.

bradthetechnut · Answer

About the only suggestion I can think of: How to Perform a BIOS or CMOS Reset and Clear the NVRAM on Dell Computers  Other than being stuck with that BIOS, is your PC working normally?

Chino de Oro · Answer

Check in the BIOS settings, under Maintenance, Enable to allow BIOS downgrade.

redxps630 · Answer

Re:which is strange because at that time it definitely was and I still have that file.

dell often removes a problematic bios version previously released because it found out some problems that it does not want customers to continue experimenting w it.

to me the only good bios update is a 100% smooth one. And do it only when absolutely no other option to solve an issue. If your pc works fine now, do not risk a bios update especially when you run into update hurdle. That should be a warning not to venture further. Bios update is intrinsically risky. Also the new bios fixes bugs that often have no relevance to you. Benefit is nil while potential risk is high.

ronyh · Answer

Yes, it's enabled, but it wouldn't have to be, because I'm actually upgrading BIOS, right?

ronyh · Answer

Yes, other than that it's working normally. Will try Your suggestion. Thank You.

bradthetechnut · Answer

Thanks for your reply.  If my suggestion works, please remember redxps630's suggestion about being careful with BIOS updates.  It can be such a sensitive process that there can be no interruptions during, like a power outage   Otherwise, the MB bricks; and that's something we really don't want to happen with your PC regardless.

redxps630 · Answer

Somehow when Dell removed 1.5 and released 1.6, the 1.5 you flashed before is now considered an unsupported bios aka “downgrade” which literally means down grade not in version number but safety. Some user reported that bios guard was built in the processor as a intel safety feature to stop bad player accessing bios. In short it is possible that bios 1.5 is now considered unsafe and thus blocked from flashing to 1.6.

Reference Intel has implemented number of security features in its 4th and later generations of possessors. These features which are described in Microarchitecture for 4th Gen include:

Intel® BIOS Guard that protects the BIOS lash from modification without platform manufacturer authorization, helps defend the platform against low-level DOS (denial of service) attacks, and restores BIOS to a known good state after an attack.
Intel® Boot Guard is a hardware-assisted authentication and protection against BIOS recovery attacks.

Optiplex Desktops

BIOS Update blocked due to unsupported downgrade

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