This article applies as of PRTG 22
Why does the PRTG setup wizard fail to restart the system after an update on Windows Server 2019, showing the error "Setup was unable to restart the computer. Please do this manually"?
Manual restart of system running on Windows Server 2019 after PRTG update
After you update to a new version, PRTG usually requires you to restart the system. Typically, PRTG restarts the system automatically. On Windows Server 2019, however, the system restart is not automatically initiated. Instead, you get the error message:
Setup was unable to restart the computer. Please do this manually.
This is because Windows Server 2019 does not forward some policies to members of a non-local user group, in this case, the PRTG Administrators group. This prevents an automatic system restart.
If you experience this issue, please restart your system manually. For a possible workaround, see this Microsoft Tech Community post.
Disclaimer:
The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.
