When attempting an in-place upgrade from Windows Server 2008 R2 to Server 2012, many admins encounter this stubborn error message. The core issue stems from outdated Active Directory schema versions that can't support newer server features.

Before proceeding, check your current schema version with this PowerShell command:

Get-ADObject (Get-ADRootDSE).schemaNamingContext -Property objectVersion

For Server 2008 R2, this typically returns 47. Server 2012 requires version 56 or higher.

1. Prepare Your Environment

Ensure you have:

• Enterprise Admin privileges
• Schema Admin privileges
• Access to the Schema Master DC
• Recent system backups

2. Running ADPREP Properly

From your Server 2012 installation media:

cd \support\adprep
adprep.exe /forestprep
adprep.exe /domainprep
adprep.exe /domainprep /gpprep
adprep.exe /rodcprep

3. Common Pitfalls and Fixes

If you receive "The version of the Active Directory schema is not compatible with this version of ADPREP", try:

adprep.exe /forestprep /skipexisting

For replication issues, force replication with:

repadmin /syncall /AdeP

Create this PowerShell script to monitor schema updates:

function Test-ADSchemaVersion {
    param($RequiredVersion = 56)
    $current = (Get-ADObject (Get-ADRootDSE).schemaNamingContext -Property objectVersion).objectVersion
    if ($current -ge $RequiredVersion) {
        return $true
    } else {
        throw "Schema version $current is lower than required $RequiredVersion"
    }
}

try {
    Test-ADSchemaVersion
    Write-Host "Schema upgrade successful" -ForegroundColor Green
} catch {
    Write-Host $_ -ForegroundColor Red
}

After successful schema upgrade, verify all DCs report the same version:

Get-ADForest | Select-Object -ExpandProperty Domains | ForEach-Object {
    Get-ADDomainController -Filter * -Server $_ | Select-Object HostName,Forest,IsGlobalCatalog
}

If schema updates continue failing, consider:

1. Promoting a new Server 2012 DC
2. Transferring FSMO roles
3. Demoting the old 2008 R2 DCs

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When attempting an in-place upgrade from Windows Server 2008 R2 to Windows Server 2012, many administrators encounter this frustrating error:

Active Directory on this domain controller does not contain Windows Server 2012
ADPREP /FORESTPREP updates. See http://go.microsoft.com/fwlink/?LinkId=113955.

This occurs even after following Microsoft's documentation, leaving many stuck in the upgrade process.

The error indicates that your Active Directory forest schema hasn't been updated to support Windows Server 2012 features. While you might have run ADPREP previously for earlier versions, each new Windows Server version requires its own schema updates.

Here's how to properly prepare your forest and domain for Windows Server 2012:

1. First, identify your schema master FSMO role holder:

netdom query fsmo

2. On the schema master, mount your Windows Server 2012 installation media and navigate to:

cd \support\adprep

3. Run forest preparation (requires Schema Admins and Enterprise Admins rights):

adprep.exe /forestprep

4. Then run domain preparation (requires Domain Admins rights in each domain):

adprep.exe /domainprep /gpprep
adprep.exe /domainprep

After running these commands, verify the schema version was updated:

Get-ADObject -SearchBase (Get-ADRootDSE).schemaNamingContext -Filter * -Property objectVersion | Select-Object -Property objectVersion

For Windows Server 2012, you should see objectVersion 56 or higher.

If you're still encountering issues:

• Ensure all domain controllers are accessible during the process
• Check replication status using repadmin /showrepl
• Verify DNS is properly configured
• Consider running ADPREP from the Windows Server 2012 R2 media if available, as it includes all previous updates

For large environments, you might want to script the verification:

$schemaVersion = (Get-ADObject -SearchBase (Get-ADRootDSE).schemaNamingContext -Filter * -Property objectVersion).objectVersion
if ($schemaVersion -lt 56) {
    Write-Host "Schema update required for Windows Server 2012"
    # Add your ADPREP execution logic here
} else {
    Write-Host "Schema is already at version $schemaVersion - ready for upgrade"
}

Before proceeding with your server upgrade:

1. Take a system state backup of your domain controllers
2. Ensure all FSMO roles are properly placed
3. Verify there's enough free disk space (minimum 32GB recommended)
4. Check application compatibility

Following these steps should resolve the ADPREP error and allow you to proceed with your Windows Server 2012 upgrade.