Fix Azure AD Sync

After changing the source of sourceAnchor that gets used for mapping on-premise users to Azure AD users (i.e. after a cutover migration or other nice things), the ImmutableId in Azure AD needs to be changed. Here's how to get this done.

Connect via Connect-MsolService

Disable Directory Sync (could take up to 72h for completion, status possibly shows false prior to that): <syntaxhighlight lang=powershell>Set-MsolDirSyncEnabled –EnableDirSync $false</syntaxhighlight>

Check status (should be false): <syntaxhighlight lang=powershell>(Get-MSOLCompanyInformation).DirectorySynchronizationEnabled</syntaxhighlight>

Generate new ImmutableId from domain account for sourceAnchor (here: objectGuid): <syntaxhighlight lang=powershell>[system.convert]::ToBase64String((Get-ADUser user).objectGuid.ToByteArray())</syntaxhighlight>

Set new ImmutableId for MsolUser: <syntaxhighlight lang=powershell>Set-MsolUser -UserPrincipalName user@contoso.com -ImmutableId "01234567890123456789=="</syntaxhighlight>

Enable Directory Sync (only possible after disabling has completed, could take 24h after enabling to complete): <syntaxhighlight lang=powershell>Set-MsolDirSyncEnabled –EnableDirSync $true</syntaxhighlight>

As a side note:

PowerShell throws a cryptic error message when trying to reenable if sync has not been fully disabled (which could take up to 72h as said before).
The AD Connect configuration tool shows a more meaningful message about the 'pending disable state'. Also it halts synchronisation when open, reenables sync by itself and features a nice retry button. So after setting the ImmutableId for each user, simply walk through configuration until the error message and retry button appear.