Adding Secondary Site Collection Administrator SharePoint 2016 PowerShell

Question

I'm trying to add a user as a 'Secondary Site Collection Administrator' using the following PowerShell script :

Get-SPSite -Limit All | %{Set-SPSite $_ -SecondaryOwnerAlias "i:0#.w|contoso\adminuser"}

when it runs it says the user cannot be found. I've tried 'i:0#.w|contoso\adminuser' and 'contoso\adminuser' and still the same. This fails to add the user as a secondary collection administrator. I have noticed one thing with this script. These are the steps :

1. Add 'contoso\adminuser' as a secondary collection administrator through the UI. click ok. redirects back to the central admin page.
2. Go back in and remove 'contoso\adminuser' from the secondary collection owner and click ok redirects back.

If I run the script again it works, it adds the user as a 'secondary collection administrator'

Do I need to add this user to the site first as a limited user or something else?

I just want to add the user to all site and sub collections.

EDIT 'contoso\adminuser' has been imported from Active Directory. If I create a new site and try and run the script again it will not add the user to the site collection. To get the script to work I have to add and the remove the user through the UI. I then run the script and it adds the user as a secondary collection owner but still gives me the error user does not exist.

I have come across cases in SharePoint Online. I think the user needs to be added some how as a Limited Access.

Another test I have just done is by sharing a folder in the team site with read permissions. Once I did that and ran the script it added the user as a secondary collection administrator

Answer 1

Sounds like the user may not exist in that site collection yet. Try using EnsureUser to ensure the user exists, then add as Secondary Site Collection Administrator.

Get-SPSite -Limit All | % {
    $_.RootWeb.EnsureUser("contoso\adminuser")
    Set-SPSite $_ -SecondaryOwnerAlias "contoso\adminuser"
}

Hope this helps!