Users do not show up in SharePoint People Search or People Picker

I had this issue with people picker in a classic mode web application in SharePoint 2013 and this site is in 2010 mode - users in certain sub-domains would not show up in People Picker.

I was aware of stsadm commands to fix this and we ran the stsadm command to hook up people picker with another domain some time back. The latest issue was that people picker was not returning users from the root domain and few sub domains.

After researching on the internet I found (contrary to my thoughts) that we could use PowerShell and not just stsadm to map People Picker to domains.

It is a good idea to first check what domains are added/mapped to the web application using the following commands:

 $wa = Get-SPWebApplication -Identity http://mywebapp.com  
 #List the Domains  
 $wa.PeoplePickerSettings.SearchActiveDirectoryDomains  

This will list the domains currently People Picker is looking up for that web application.

I used the following script to map our AD forest to People Picker:

 $wa = Get-SPWebApplication -Identity http://mywebapp.com  
 $ad = New-Object Microsoft.SharePoint.Administration.SPPeoplePickerSearchActiveDirectoryDomain  
 $ad.DomainName = "domain.com"  
 $ad.IsForest = $true  
 $wa.PeoplePickerSettings.SearchActiveDirectoryDomains.Add($ad)  
 $wa.Update()  

If you run the first block of script again it should list the new domain and you should be able to see people results in the People Picker immediately.