Hey everyone! I could use some help. After updating to the April 2026 cumulative update (version 26200.8246), I'm running into an error when I try to apply a cumulative .msu patch to an offline WIM or VHDX. The error message I get is: "WARNING: Failed to add package" along with an error code 0x800401e3, which suggests problems with the Unattend.xml file from the .msu package. I've tried including the September 2024 update (KB504308) in the same folder, but that doesn't work either. Interestingly, the same files work fine on a device running the March 2026 cumulative update. Has anyone else faced this issue? I'm thinking of logging it with Microsoft, but I wanted to see if there's any insight here first. Thanks!
3 Answers
I’m having similar issues trying to apply this patch to a clean offline Windows 11 25H2 image straight from the ISO. No luck with or without the checkpoint MSU, which is crucial for applying language packs and Features on Demand (FoD). It’s strange because everything works perfectly on online systems. Must be a bug with this update.
We had a different issue where Windows blocked some Shortcut files we injected after the KB5083769 update due to them having the Mark of the Web. They worked fine for months before that. It might be connected to some changes made in that KB, but not sure if it exactly helps with your issue.
This is odd, but I found that while Add-WindowsPackage fails, using 'dism.exe /image:C:mountdir /PackagePath:C:PackagePathKB5083769.msu' worked for me. Just make sure the checkpoint MSU is in the same folder as the KB5083769 file. I'm currently waiting for my WIM to commit to see how it goes.
You're right! I had tried DISM before and it didn't work, but after removing the MoTW and trying DISM again, it’s finally patching successfully! I’m going to do a thorough re-test tomorrow, but I'm really grateful for your guidance!
I wish that were the issue, but I've already checked and removed the Mark of the Web from the downloaded files, and I'm still facing the same problem with the update not applying.