Login in to the CUCM system and make sure all the essential services are running by CLI.
Admin: utils service list page
Try to restart Cisco Tomcat service by following command. Usually, that fixed the above issue.
Admin: utils service start Cisco Tomcat
Win+R> run > gpedit.msc > Computer Configuration > Administrative Templates > System > Credentials Delegation > Encryption Oracle Remediation>
Now set it to Enabled, and set the protection level to Vulnerable as in the below image, and click on the OK button.
Start Menu > cmd > Run as administrator and paste below lines together:
FOR %F IN ("%SystemRoot%\servicing\Packages\Microsoft-Windows-GroupPolicy-ClientTools-Package~*.mum") DO (
DISM /Online /NoRestart /Add-Package:"%F"
)
FOR %F IN ("%SystemRoot%\servicing\Packages\Microsoft-Windows-GroupPolicy-ClientExtensions-Package~*.mum") DO (
DISM /Online /NoRestart /Add-Package:"%F"
)Wait for 100% then try again.