BIOS update blocked

Question

Hello community. I'm stuck trying to downgrade my Latitude 5531's BIOS from the current v1.27.0: Whereas the Important Information section of the BIOS download page says:

"Once the BIOS is upgraded, you cannot downgrade the BIOS to versions earlier than 1.9.0. BIOS downgrades are restricted when there are security updates and important fixes with earlier versions that impact the functionality of the system."

I am unable to downgrade to any version later than 1.9.0. The update process fails with a "BIOS Update blocked due to unsupported downgrade." message, whichever version I try.

Why can't I downgrade to e.g. BIOS 1.18.0? Am I missing something?

Dellatore · Accepted Answer

I return with good news: I was finally able to circumvent the confounded downgrade restriction and return BIOS to the factory original v1.18.0 using the guide at this link as a starting point: https://github.com/vuquangtrong/Dell-PFS-BIOS-Assembler/blob/master/README.md . I had to rework the code given there as it contained a few bugs and did not produce the desired results on BIOS images for more recent laptop models such as the Latitude 5531/Precision 3571. I also modified the update procedure as given since it does not work for the 5531. As a result of these changes I can downgrade BIOS for both older and newer laptop models to whatever version I like.

Many thanks to all for your support.

Cheers.

JOcean · Answer

You are not missing anything, that downgrade is blocked. This information from the support page states as follows:

"Once the BIOS is upgraded to version 1.9.0 or later, you cannot downgrade the BIOS to versions earlier than 1.9.0. BIOS downgrades are restricted when there are security updates and important fixes with earlier versions that impact the functionality of the system."

Dellatore · Answer

@JOcean​ Thanks, but I was referring to the current v1.27.0. I can't downgrade to v1.18.0 which, needless to say, is later than v1.9.0. Anyone else have a sensible explanation?

JOcean · Answer

@Dellatore​ Interestingly enough the disclaimer appears to have been changed since I left my reply. It now states: Once the BIOS is upgraded to version 1.9.0 or later, you cannot downgrade the BIOS to earlier versions. BIOS downgrades are restricted when there are security updates and important fixes with earlier versions that impact the functionality of the system. The important phrase is earlier versions and NOT earlier than 1.9.0. So it would appear earlier versions than anything above 1.9.0 such as 1.27.0 to 1.18.0. I may be incorrectly reading your post or the phrase from the BIOS page. Possibly someone else can give you a sensible explanation. Sorry I was unable to help.

Dellatore · Answer

The disclaimer regarding v1.27.0 is quoted verbatim in my first post and hasn't changed. "earlier than 1.9.0" seems pretty clear to me.

I also own a 5310 with the same disclaimer for BIOS v1.25.0 currently running on that machine. It's worded slightly differently but to same effect:

"Once the BIOS is upgraded, you cannot downgrade the BIOS to version 1.18.0 or earlier. BIOS downgrades are restricted when there are security updates and important fixes with earlier versions that impact the functionality of the system."

I can confirm the BIOS can be downgraded from v1.25.0 to v1.19.0 on that system, so this statement holds in that case.

Looks like Dell has its head in the sand for the 5531. Some Arabica roast, perhaps?

bacillus1 · Answer

not sure if this bios setting applies to your system but on my xps there is a bios setting under maintenance>bios downgrade and you need to check the check box on the right pane to allow bios downgrade.

hth

Dellatore · Answer

@bacillus1​ It sure does and there certainly is such an option in BIOS settings - the update won't even proceed when called from the boot menu if the option is disabled. So yes, it's enabled and there is no logical reason for the downgrade not to be executed. It's another item I can add to the list of oversights related to this model. The sloppiness continues.

HedgeFundManager · Answer

I installed a new UEFI/BIOS on my Latitude 5440 earlier and it seems to be problem free. Mind you all I do is pretty mundane.

user_06b144 · Answer

Hi Dellatore - is the procedure and necessary files available somewhere? (I have a similar problem). Thanks - Michal

Dellatore · Answer

Hello Michal. I don't think they are since I devised these on my own and didn't upload them anywhere, although I would be happy to share them with you here. Note that it is NOT possible to downgrade Intel ME using this method and a CH341A-based programmer is required to accomplish this. It's not a trivial procedure.

Cheers.

user_06b144 · Answer

Hello,thanks for your answer. Ah - I'll try to solve the problem in a different way.Have a nice day,Michal

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BIOS update blocked

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