A server-side database availability group administrative operation failed. Error: The computer account ‘DAG1′ could not be validated. Access was denied. Check that the current user (NT AUTHORITY\SYSTEM) has permissions to create computer accounts in the domain or to claim the computer account.

This error occurs in most of the cases when you add a DAG member to Exchange 2010 SP1 first time. The error generally gets displayed like:

Error:
A server-side database availability group administrative operation failed. Error: The operation failed. CreateCluster errors may result from incorrectly configured static addresses. Error: The computer account ‘DAG1′ could not be validated. Access was denied. Check that the current user (NT AUTHORITY\SYSTEM) has permissions to create computer accounts in the domain or to claim the computer account. [Server: MBX01.domain.local]

A server-side database availability group administrative operation failed. Error: The computer account ‘DAG1′ could not be validated. Access was denied. Check that the current user (NT AUTHORITY\SYSTEM) has permissions to create computer accounts in the domain or to claim the computer account.

Solution:

First of all we have to tackle the access denied part of it and it can be cleared by checking and assigning the required permissions.

Error is also showing that static IP has miss-configured so ensure that it is assigned perfectly as per the necessity

There might not be a DAG1 account created by where as DAG account could be there which an Exchange Console formulate without any problems/error. So ensure that DAG1 account has created in the place.

You can also simply remove DAG pre-stage DAG user in AD and assign full permission on DAG Object; don’t forget to deactivate the DAG computer A/c.

That’s all; it should be get running as smooth as you sail in a lake.