#PSTip Be cautious with profile customizations and PowerShell Workflow

When working with Windows PowerShell Workflow, there are things to be aware of which can break workflow from working. One such thing is customizations made in the PowerShell profile.

Let’s start by defining an example workflow we can work with:

Workflow Get-RemoteService {
	Get-Service -PSComputerName $PSComputerName
}

When invoking the workflow I got the following errors on my computer:

PS [3]: Get-RemoteService -PSComputerName srv1

WARNING: The binding of default value ‘True’ to parameter 'Keep' failed: Cannot bind parameter ‘Keep’ to the target. Exception setting "Keep The Wait" and "Keep parameters cannot be used together in the same command." 

Cannot find drive. A drive with the name 'Scripts' does not exist.
+ CategoryInfo : ObjectNotFound: (Scripts:String) [], ParentContainsErrorRecordException
+ FullyQualifiedErrorId : DriveNotFound
+ PSComputerName : [localhost]
What is going on here? Let\`s start by looking at the warning: Cannot bind parameter 'Keep' to the target.

This one is hard to track down without knowing that workflow actually uses PowerShell jobs under the hood. The -Wait and -Keep parameters mentioned in the warning message is available on the Receive-Job cmdlet. The two parameters belongs to different parameter sets, and can not be used together. In my case I had the following defined in my PowerShell profile:

$PSDefaultParameterValues.Add("Receive-Job:Keep",$True)

To verify this was causing the problem I removed Receive-Job from $PSDefaultParameterValues and re-ran the workflow:

$PSDefaultParameterValues.Remove("Receive-Job:Keep")
Get-RemoteService -PSComputerName srv1

This resolved the warning:

PS [5]: Get-RemoteService -PSComputerName srv1

Cannot find drive. A drive with the name 'Scripts' does not exist.
+ CategoryInfo : ObjectNotFound: (Scripts:String) [], ParentContainsErrorRecordException
+ FullyQualifiedErrorId : DriveNotFound
+ PSComputerName : [localhost]

For the second error, we can see an error regarding the Scripts: drive. This is a PSDrive defined in my PowerShell profile, which is the current location in my PowerShell session. Since workflow runs in it`s own runspace, the drive cannot be found.

After changing the current directory to C: which is also available to the workflow runspace, the workflow runs without issues.

cd c:
Get-RemoteService -PSComputerName srv1

The easiest way to exclude profile customizations from breaking a workflow is by launching powershell.exe/powershell_ise.exe with the -NoProfile switch. If the workflow then runs without issues, you should start looking at your PowerShell profile to see what might be interfering with workflow.