KB5009624 Causes a Loop “Continuous Restart/Reboot” on all Windows Servers with any Role. As per Microsoft Support the exact reason has not been figured out. There are first impressions but nothing concrete.
Root Cause Analysis
Microsoft Support is still working on this issue to figure out the exact reason why KB5009624 causes a continuous restart/reboot on all Windows Servers with any Role. The recommendation is to not install “Monthly Rollup KB5009624” for the time being.
For customers who already installed KB5009624 the Solution basically is to start the Windows Servers in “SAFE MODE” and NOT with “Last Known Good Configuration”. “Last Known Good Configuration” can cause a lot of problems and headache especially on Domain Controllers, Hyper-V Servers, Exchange Servers and other Application Servers.
Once the Servers has been started in “SAFE MODE” basically uninstall KB5009624 over “Programs and Features” and restart the Windows Servers again. It should work fine again.
If you started the Windows Servers with the “Last Known Good Configuration” and experience any kind of issues/problems, the only one option to fix this problem is to restore the Servers from backup.
Good luck !