On Hosts running VMServer and ShadowProtect (backup solution)
Increasing the number of processors to 2, and turning off Shadow Protect has worked reliably
Once the upgrade is finished I turn Shadow Protect back on (deleting the chain first)
I also was stupidly running the upgrade from a virtual disk mounted within the machine, switched to using the file attached to the virtual drive
Currently I'm failing on HyperV but I'll see how it goes disabling the HyperV virtual adapter, in the end, I succeeded without doing this
Free Space required 20gb
2 Processors
Deleted an old version of Microsoft Endpoint
For HyperV, client I think has to be Gen2
I failed several times on the most recent Server2022 Iso, but just had success with the August 2021 iso