Thanks for your reply @abbodi1406 So I did indeed restore from an image backup to retry with an inplace-upgrade, for which I created a proper 18362.329 iso. (18362.329.190828-1651.19H1_RELEASE_SVC_PROD3_CLIENTMULTI_X64FRE_DE-DE.ISO) And the results are quite surprising: Code: c:\Windows\WinSxS before (fresh 18362.327): 6,1GB c:\Windows\WinSxS after applying abbodi's hack and cleaning up: 7,8GB c:\Windows\WinSxS after inplace-upgrade to 18362.329 and cleaning up: 3,3GB c:\Windows before (fresh 18362.327): 10,7GB c:\Windows after applying abbodi's hack and cleaning up: 12,9GB c:\Windows after inplace-upgrade to 18362.329 and cleaning up: 5.8GB Windows Update works and finds no longer any uninstalled updates. Code: Microsoft Windows [Version 10.0.18362.329] (c) 2019 Microsoft Corporation. Alle Rechte vorbehalten. C:\Windows\System32>systeminfo <...> Hotfix(es): 4 Hotfix(e) installiert. : KB4511555 : KB4503308 : KB4515530 : KB4512941 <...> I am still very surprised and confused by the huge differences in numbers compared to .327 vs .329 so I assume that windirstat gets a little confused by WinSxS, how could that be almost a 50% difference in size? In the end I have compared the filesizes of the compressed backups of the entire installations and this gives some more realistic numbers. Code: Highly compressed backup (after applying abbodi's hack and cleaning up): +1.04GB Highly compressed backup (after inplace-upgrade to 18362.329 and cleaning up): -0.14GB This does indeed mean that .329 is considerably smaller than .327, this appears to be a very optimized CU (or atleast it finally replaces a tons of patches that were not yet cumulated). Absolutely nothing like 50% smaller, but definitely noticable. The highly compressed +1.04GB (compared to .327) shows that the extra 2.2GB diskspace (as reported earlier) was indeed a real number. I admire the smart work you've put into your hack, but these numbers speak for themselves. And it will also make me sleep much better, I didn't feel comfortable with reinjecting ancient stuff from a base build that is months old. I can only advise people to try an inplace-upgrade first and see if this fixes the problem (it did for me).