Handling Domain Join Errors - powershell

Question

I have created a basic script to add a PC to the domain. Although this works there is room for error, and I want to put in some error handling.
do {
Add-Computer -DomainName $Domain -Credential(get-credential)
} while (!$?)
Using !$? runs the while loop while the last command is not successful.
However, there are various errors that return. Whether the PC is off the network, incorrect user ID or password, or domain specification, I want to be able to handle those errors and display something meaningful.
One of the errors returned
Add-Computer : This command cannot be executed on target computer('PCName') due to
following error: Logon failure: unknown user name or bad password.
At line:1 char:13
+ Add-Computer <<<< -DomainName $Domain -Credential(get-credential);
+ CategoryInfo : InvalidOperation: (PCNAME:String) [Add-Computer], InvalidOperationException
+ FullyQualifiedErrorId : InvalidOperationException,Microsoft.PowerShell.Commands.AddComputerCommand
Working with error handlers in lets say VBA, an error ID is given, and using if statements you can do something with it.
The FullyQualifiedErrorID in the error above is the same across all errors received for different reasons, so I do not believe I can use that.
How can I capture the specific error "Logon failure: unknown user name or bad password." or other errors and display a meaningful message so the admin can take appropriate action?

Answer 1

If nothing else you should be able to use the error message for distinguishing between errors:
do {
$joined = $true
$cred = Get-Credential
try {
Add-Computer -DomainName $Domain -Credential $cred -ErrorAction Stop
} catch {
$joined = $false
switch -regex ($_.Exception.Message) {
'.*unknown user name.*' { ... }
'.*domain does not exist.*' { ... }
...
default { 'Unexpected error' }
}
}
} until ($joined)
Note that you'll need to set the error action to Stop (-ErrorAction Stop), because otherwise the errors would be non-terminating and thus not catchable.

Answer 2

Use it with the -ErrorAction parameter:
Add-Computer ... -ErrorAction SilentlyContinue -ErrorVariable computerError
The ErrorVariable is an array, so the resulting error will be stored in:
$computerError[0]
To use the same variable over and over again, use a + in front of the var name:
Add-Computer -ErrorVariable +manyErrors
And the last error will always be:
$manyErrors[$manyerrors.count - 1]
To get the last error code if it has a corresponding Win32 error code then run the following
$manyErrors[$manyerrors.count - 1].Exception.InnerException.NativeErrorCode
And then if you gather the potential error codes you could do the following
if ($manyErrors[$manyerrors.count - 1].Exception.InnerException.NativeErrorCode -eq 1)
{
Write-Host error happened
}
elseif ($manyErrors[$manyerrors.count - 1].Exception.InnerException.NativeErrorCode -eq 2)
Write-Host other error happened
}