Good Morning,
I've come across a strange error with the import-pssession cmdlet, and wanted to run it by the experts. I'm using it in a larger account creation script the import the exchange cmdlets from an exchange server to create a mailbox. In testing it all in the shell the below commands work fine:
$session=New-PSSession-ConfigurationNameMicrosoft.Exchange-ConnectionUrihttp://$exchangeserver/powershell
Import-PSSession-session$session-AllowClobber-DisableNameChecking
However, when I run them in my larger script, I get the below error:
Import-PSSession : Cannot convert null to type "System.DateTime".
At C:\scripts\importbug.ps1:8 char:5
+ Import-PSSession -session $session -AllowClobber -DisableNameChecking
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : MetadataError: (:) [Import-PSSession], ArgumentTransformationMetadataException
+ FullyQualifiedErrorId : RuntimeException,Microsoft.PowerShell.Commands.ImportPSSessionCommand
Now I couldn't for the life of me figure out what Import-PSSession would be doing with any dateTime values, or even what null variable I was passing to it. After deconstructing my script I narrowed it down the following minimum code to illustrate the error:
FunctionGet-Exchangecmdlets {
param(
[string]$ExchangeServer,
[datetime]$date
)
$session=New-PSSession-ConfigurationNameMicrosoft.Exchange-ConnectionUrihttp://$exchangeserver/powershell-AllowRedirection-AuthenticationKerberos
Import-PSSession-session$session-AllowClobber-DisableNameChecking
}
Get-Exchangecmdlets-ExchangeServer'exchangeserver1' #This throws the error
Get-Exchangecmdlets-ExchangeServer'exchangeserver1'-Date"10/10/2013" #This does not
So it seems that when import-pssession runs, it validates all the variables in its parent function. Since $Date wasn't specified, it was null, which can't be converted to DateTime, hence the error. This error also appeared with parameters using the [validatescript] setting, such as:
FunctionGet-Exchangecmdlets {
[cmdletbinding()]
param(
[string]$ExchangeServer,
[ValidateScript({test-path (Split-Path-Path$_-Parent)})]
[string]$ErrorLog
)
$session=New-PSSession-ConfigurationNameMicrosoft.Exchange-ConnectionUrihttp://$exchangeserver/powershell-AllowRedirection-AuthenticationKerberos
Import-PSSession-session$session-AllowClobber-DisableNameChecking
}
Get-Exchangecmdlets-ExchangeServer'exchangeserver1' #This throws the error
Import-PSSession : Cannot bind argument to parameter 'Path' because it is an empty string. At C:\scripts\importbug.ps1:10 char:5 + Import-PSSession -session $session -AllowClobber -DisableNameChecking + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : InvalidData: (:) [Import-PSSession], ParameterBindingValidationException + FullyQualifiedErrorId : ParameterArgumentValidationErrorEmptyStringNotAllowed,Microsoft.PowerShell.Commands.ImportPSSessionCommand
I didn’t test the other validation methods, but I suspect they’ll all throw the error.
Once identified this is easy enough to work around, I simply made a separate function for the import-pssession with no optional parameters and no validation. However, since optional parameters should only be validated if a value is provided, this seems rather bug-like to me. Nothing in the documentation for Import-PSSession jumped out at me as suggesting that variables are re-processed or anything like that.
Thoughts?
