Cannot remove DC from Domain

Hi

Im am trying to demote a domain controller but im getting the follwing error

‘The Operation faile because:

A domain controller could not be contacted for the domain that contained an account for this computer. Make the computer a member of a workgroup the rejoin the domain before retrying the promotion.

“The specified domain either does not exist or could not be contacted”‘.

The server is not the last DC and i can ping the the oher DC