Either Active Directory doesn’t exist, or it can’t be contacted

 https://baswijdenes.com/fix-installing-exchange-cu-multiple-errors-active-directory/

FIX: Installing Exchange CU multiple errors Active Directory

Table of Contents

• ‘Either Active Directory doesn’t exist, or it can’t be contacted.‘, what?
• So, what is the issue here?
  • How can I resolve this?
• Full error message

‘Either Active Directory doesn’t exist, or it can’t be contacted.‘, what?

With the Exchange Security updates two weeks ago I got a nice list of errors while updating an Exchange server.

I went through the steps and at the last step where Exchange checks if the updates can be installed, I got quite a few errors. The main ones were the Active Directory error messages.

My account was in the correct groups and yet it looked like it couldn’t access Active Directory at all and because he cannot access active directory you will get all other error messages.

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So, what is the issue here?

The main issue is that the Exchange Update cannot update the Active Directory schema because the Exchange server is not in the same site as the Schema master.

For more about the Schema master click here

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How can I resolve this?

Make the Domain Controller in the same site as the Exchange server the Schema master. This may be temporary to install the updates. In the below steps I’ll explain how you can do that.

Open PowerShell as Administrator

Let’s first check which server is the schema master before continuing, so that you can always adjust this to the old situation.

Get-ADForest | Select-Object SchemaMaster

Now we know which server was the Schema Master we can now move the role to a server in the same site as the Exchange server.
I’ve used $ENV:LOGONSERVER as the new Schema Master because usually you logon to a Domain Controller in the same site.

Move-ADDirectoryServerOperationMasterRole -Identity $ENV:LOGONSERVER -OperationMasterRole SchemaMaster

Now try to install the exchange updates again and revert back to the old Schema Master after you’re finished.