Why does the 2023-05 CU for Windows 11 Version 22H2 for x64 contain several wim images and is 9GB in size in WSUS?

Question

I noticed a large increase in the size of Windows 11 patches in WSUS starting April 2023;
The May 2023 W11 cumulative update is the same way-- many files that are multiple GB's in size according to WSUS, but it is only a single update file that is much smaller at the update catalog?

Case in point this patch:

2023-05 Cumulative Update for Windows 11 Version 22H2 for x64-based Systems (KB5026372)

https://www.catalog.update.microsoft.com/Search.aspx?q=2023-05%C2%A0Cumulative%C2%A0Update%C2%A0for%C2%A0Windows%C2%A011%C2%A0Version%C2%A022H2%C2%A0for%C2%A0x64-based%C2%A0Systems%C2%A0(KB5026372)

It's only 275 MB at the update catalog-- a single MSU file.

However If we look at the same patch in WSUS to see its file details, i.e. using powershell:

(Get-WsusServer).GetUpdates() | Where {$_.Title.Contains('2023-05 Cumulative Update for Windows 11 Version 22H2 for x64-based Systems (KB5026372)')} | foreach {$_.GetInstallableItems().Files | Select Name, OriginUri, TotalBytes} | Format-List

This outputs a list of many files including several .WIM images, totaling ~9.2 GB in size!

April's CU was similar, but the March CU wasn't humongous like this.

This seems like possibly a mistake?

Answer 1

It is not by mistake - this is UUP

https://www.ajtek.ca/guides/how-to-prepare-for-on-prem-wsus-uup-updates/