Z600 new Secure Boot Certificate

[etsok]

I have several z600 systems running Windows 11 with no problems. What should I do to prepare for the Secure Boot Certificat update that is due in 6/26?

[Paul_Tikkanen]

The z600s don't support secure boot, so no action is needed.

[Challenger392]

Ran in to this yesterday.

Got win11 25H2 installed over Win10 22H2 on a Z600 Workstation PC.

All was running fine until what I believe was last Preview Update 4-2026 last evening. 

Let it install. I came to check PC today and saw that at BIOS boot screen was Boot from HDD and blinking cursor only. Would not boot past this. Checking everything and used recovery media to check for boot start up issues. Still failed to correct the boot stall. 

Re-cloning drive back to Win10 image and going to retry Win11 install and see what happens again. Trying a different drive as well.

Worried that MS may block older PCs that don't have Secure Boot or updated Certs. 

I maybe missing something else as well. 

Any one else seen this or have feedback to may prevent this?

[Paul_Tikkanen · Accepted solution]

I'm running W11 25H2 on a HP 8200 Elite CMT with an Intel i7-2600 processor.

The PC has a UEFI BIOS and does not support secure boot.

W11 25H2 has been working fine on it since I upgraded the PC from 24H2>25H2, so I do not believe that Microsoft has recently decided (like in the last few days) to prevent W11 from running on PC's that do not support secure boot.

The only thing they have done since W11 came out was to prevent 24H2 and newer builds of W11 from running unless the processor supports SSE4.2.

I had to leave two of my PCs on W11 23H2 that have Intel Core 2 Duo processors and those do not support SSE 4.2.

[Challenger392]

OK got word that Windows 11 will work with secure boot disabled and should not prevent windows from booting normally. So issue I saw with the z600 may have been fauly SSD media. I'm now trying HDD media that i've re-cloned the original drive to again and now in process of re-installing Windows 11 25H2 back on the z600 PC. 

Will update with final results. Fingers crossed. 

[Challenger392]

Ya I found out about the SSE4.2 a while ago. Thats one first thing I check before attempting any Win11 upgrades. If it's 4.2 supporting then I'll make the upgrade. If not, then I'll probably not use that HW anymore or load 23H2 as last resort. 

[Challenger392]

Welp, it was not the SSD media. So I cloned the 2nd HDD to the working Win 10 image.
Got Win 11 25H2 installed. Rebooted and power cycled the z600 PC a few times during this stage with out any boot issues.

Started Windows Update. All was good until 4-2026 Preview was seen. I took another image of this drive before proceeding to be safe. Thank god for back up sw.

Started the preview update. It got to 30% installed. Rebooted here. Rebooted ok past BIOS. Then continued updating and installing here.
Got to 100% and about a minute or two the PC rebooted.
And now it won't go past the Booting from HDD BIOS screen.

Repairing Startup did solve. Attempted to remove quality update and didn't find anything. Attempted to remove the other updates and that failed as well.

So will re-imaage drive and pause all updates as this seems most recommended.

Not sure what is causing this issue. Will try and so some research. Seems to be a known issue for others as well for this one update causing issues. Odd that I have a Z210 SFF PC with win11 25H2 on it and it's got this update already installed back on 5/2.

Does this particular update need to be installed or can it be bypassed to attempt to get the May 2026 update? I see that had problems for some as well. Oy vay.

Any feedback on this appriciated.

Thank you.

[Challenger392]

Just had a thought, wondering if I could get a later Win11 25H2 build and put it to USB and try to install on the z600 PC? Something this month or may have to wait a bit longer? No sure if this would have been fixed by MS in later builds of Windows.

[Paul_Tikkanen]

There is a way you can just prevent that specific 4-2026 Preview from installing and let all other updates get installed.

Download and run the Microsoft Hide Windows Update utility that I zipped up and attached below:

When you run the utility, it will find updates pending to install.

Check the box to hide the update.

The utility will run again and report the problem is 'Fixed.'

Exit the utility, restart the PC. and that update should not show up again.

I just hope that whatever is in that update preview has been fixed or doesn't cause your PC to quit working when the next W11 cumulative update comes out.

[Challenger392]

YOU ARE A GEM. THANK YOU.

I totally forgot that that little app. I had it on my external USB flash drive that I use to get drivers and such on to new PC builds. 

As of last night after re-imaging Win10 then re-installing Win11. I did see the 4-2026 Preview update seen there again, but I selected the X for it. Just got to this PC this morning and checked updates and it's not listed. Getting a 5-2026 security update now and one other not related to Previews. I did run the WU Show Hide app in both modes an the 4-26 update wasnt' seen. Going to recheck this again later today. 

I'm also tryin a later Win11 install build just to see if this helps get past anything 4-2026 Preview. 

Ya, hoping this is correctly by MS fully. Hoping I can keep using older PC HW with out issues. I Know at some point, I'll probably not be able to upgrade them at all. Wondering what it will be like at Win12...

Again, thank you for the reminder. This will help me get the PC back to it's owner sooner.