Found it. Error is related to https://github.com/xapi-project/xen-api/issues/4141

Somehow, the PCIe bus address of the server's ASPEED VGA adapter changed.

I got the new bus address with lspci and edited state.db accordingly. Works now. However, this seems to be a very strange bug.

stormi created this issue in xapi-project/xen-api open XAPI failing to initialize after GPU removal? #4141

Hi, I add the same thing last week. Yes it was a driver issue that got through Windows Update. I actually download the latest driver from Citrix and it solved my issue, I also de-activate the Windows update tools. I didn't try to inject the drivers, I restore a backup from the night before.