Positional Parameter issue

I have a script that ends up creating a variable for each user in AD ($variableResult), iterating through each user. I have tested everything outputting to a log file - all fine. The last stage is to get it to write changes ($variableResult) to AD Attribute (POBox). It compares the 2 and if they are different it will overwrite.

This is the issue that I have:

Set-ADUser: Cannot bind parameter 'Identity'. Cannot convert value "CN=xxx,OU=Windows 10,OU=UserAccounts,OU=xxx,OU=xxx,DC=xxx,DC=xxx" to type "Microsoft.ActiveDirectory.Management.ADUser". Error: "Cannot convert the "CN=xxx,OU=Windows 10,OU=UserAccounts,OU=xxx,OU=xxx,DC=xxx,DC=net" value of type "Deserialized.Microsoft.ActiveDirectory.Management.ADUser" to type "Microsoft.ActiveDirectory.Management.ADUser"."

Here is what is stored in the variable:

PS > $variableResult                    
HQCSHOFF

I have modified the script to only search for my user name, set the POBox incorrectly in AD, so that the script should correct but instead i get this error:

if( $user.POBox -ne $variableResult ) {
    set-aduser $user -Replace @{POBox="$variableResult"}
}

The error implies that $user is an object coming from a remote session (Deserialized.Microsoft.ActiveDirectory.Management.ADUser) and what the error is stating is that this object cannot be coerced into an ADUser instance (the parameter type of -Identity):

Get-ADUser [-Identity] <ADUser> ...

After testing this myself, this is indeed the case:

$user = Start-Job { Get-ADUser $env:USERNAME } |
    Receive-Job -Wait -AutoRemoveJob

# Get-ADUser: Cannot bind parameter 'Identity'. Cannot convert value "CN=...
Get-ADUser $user
# InvalidArgument: Cannot bind parameter 'Identity'. Cannot convert value "CN=...
[Microsoft.ActiveDirectory.Management.ADUser] $user

The simple workaround is to use one of the properties from the deserialized object that can be used to construct an ADUser instance:

• A distinguished name
• A GUID (objectGUID)
• A security identifier (objectSid)
• A SAM account name (sAMAccountName)

In summary, this should solve the problem:

if ($user.POBox -ne $variableResult) {
    Set-ADUser $user.DistinguishedName -Replace @{ POBox = $variableResult }
}

See Deserialized objects for more details.