XPS 14 9440, crashing after 1.21.0 Bios Update

@Realistic_Speech_456 ,

XPS 14 9440

my laptop updated to BIOS 1.21.0.0.

• KERNEL_SECURITY_CHECK_FAILURE (139) - Failing at nt!PpmIdleExecuteTransition / nt!PoIdle

• KERNEL_MODE_HEAP_CORRUPTION (13a) - Failing at nt!ExpWorkerThread

• KMODE_EXCEPTION_NOT_HANDLED (1e)

• PAGE_FAULT_IN_NONPAGED_AREA (50)

1. Hardware Diagnostics: Ran Dell ePSA and Windows Memory Diagnostic. Both passed completely without errors.

2. Software Isolation: Did a completely clean, fresh install of Windows 11. The BSODs continued exactly the same way on a fresh OS.

3. Stress Testing: Ran OCCT, and the system completely hard-crashed and rebooted during the test.

4. BIOS Downgrade: I tried rolling back to a stable version (v1.13.0) using both the Windows executable (/forceit) and the USB BIOS_IMG.rcv recovery method (Ctrl+Esc). Both are completely blocked by the system, likely due to an Intel ME security revision update.

5. Current Status: I'm stuck on an unstable BIOS that crashes my kernel during idle states (C-States), and I can't roll back. I suspect either the 1.21.0.0 firmware has a massive bug regarding voltage regulation/idle transitions, or my motherboard/VRM/soldered RAM coincidentally died at the exact time of the update.

Has anyone else faced this with BIOS 1.21.0.0 on the 9440? Did you manage to bypass the downgrade lock somehow, or did you just have to get the motherboard replaced by Dell ProSupport?

Thanks in advance!

1. That's a start, but yeah ... it's very basic

2. Good. Hmm ...

3. I love OCCT.

4. Does it look like all the sub-parts got updated as well ? (you can run the Windows installer, see versions, then bail out).

I thought the switch was simply /f ?

Unless it's a Milestone version, you should be able to back-flash to previous version in chronological list. Remember that there is also a BIOS option that blocks BackFlashing/DownGrading BIOS.

Finally, if you want to prevent BIOS-upgrades via Windows-Update, you set (in BIOS) UEFI Capsule Updates to disabled.

Thank you, @Tesla1856 

Checked the windows installer and actually there were a few other drivers updates, which I rolled back prior to reinstalling windows completely. Didn't fix. And after windows reinstall, I was running with no other updates.

The 1.21.0 bios version actually has the downgrade protection. On the description of its download page it says "Once the BIOS is upgraded, 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"

@Realistic_Speech_456​ ,

Thank you, @Tesla1856 

1. Checked the windows installer and actually there were a few other drivers updates, which I rolled back prior to reinstalling windows completely. Didn't fix. And after windows reinstall, I was running with no other updates.

2. The 1.21.0 bios version actually has the downgrade protection. On the description of its download page it says "Once the BIOS is upgraded, 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"

1. NO. I'm talking about the XPS_14_9440_1.21.0.exe Installer-File.

2. Seems that either Dell has changed their wording on BIOS Updates, or all recent BIOS updates for this laptop are "Milestone versions".

If you find that all the sub-parts of XPS_14_9440_1.21.0.exe DID INDEED install (and update all the sub-components properly) I think you will just have to wait for another version to be released. 

I suspect I may be seeing the same issue reported here, although it is for a different Dell XPS model and firmware version.

My Dell XPS 16 9640 laptop running Windows 11 Pro has frozen and restarted without warning repeatedly since a Windows update on Friday March 27. According to Windows Update History that was a Dell Inc. Drive Update. It included a firmware update. Those issues are new, prior to that update the laptop was stable.

Based on subsequent research I think the firmware installed was this file: XPS_16_9640_1.20.0.exe. I am unable to install an earlier version of the firmware.

The freezes and restarts occur much more frequently when power is plugged in. The laptop freezes and/or restarts too often to be usable if plugged in. It is is almost stable when not plugged in, the same symptoms occur but separated by several hours rather than minutes.

I have applied all updates available from Dell and all Microsoft Windows 11 updates, including KB5086672. None of the updates have fixed this new behavior.

@xps_owner_2026​ ,

My Dell XPS 16 9640 laptop running Windows 11 Pro has frozen and restarted without warning repeatedly since a Windows update on Friday March 27.

1. According to Windows Update History that was a Dell Inc. Drive Update. It included a firmware update. Those issues are new, prior to that update the laptop was stable.

2. Based on subsequent research I think the firmware installed was this file: XPS_16_9640_1.20.0.exe. I am unable to install an earlier version of the firmware.

2. Possibly

1. Interesting you found it listed, because after one of my XPS laptops received (and applied on next a reboot) some UEFI-Capsule updates thru Windows-Update, there was no record of it in the history logs (like the others and is normal).

Coincidentally, there were actually two ... one a BIOS-Firmware and the other was a SSD-Firmware. They got queued-up and applied (separately) on the next two consecutive reboots.

Needless to say, it was an over-sight to even have that BIOS option enabled, and after all that action (that I was powerless to stop) I turned UEFI-Capsule updates OFF in BIOS (as I usually keep it on my machines).

If yours was actually called "Dell Inc. Drive Update" it might have been a firmware-update for the SSD ... our SSDs are usually Dell-OEM versions and only supported by Dell. As such, any firmware updates for them normally only come from Dell, like in the File-Library. Or, apparently now thru Windows-Update when published by Dell, for Dell computers, with certain exact hardware signnatures.

Finally, I'll say that both of the Firmware updates my laptop received that night applied and worked properly.