Try Catch still not working in Powershell V2 even with “$ErrorActionPreference = “Stop”

Question

I'm running the exact same code on three computers. On computer "A" which is PSV2 (which I'm not allowed to upgrade to PSV3), the following code doesn't do anything EXCEPT print the error Message at the end of execution.

$ErrorActionPreference = "Stop"
TRY { $ErrorActionPreference = "Stop"
New-Item -Type File $("C:\Windows\System32\NewFile.Txt") -ErrorAction Stop }
CATCH [System.UnauthorizedAccessException],[System.UnauthorizedAccessException]
{ Write "Rerun with elevated permissions" }
FINALLY { Get-ChildItem $("C:\Windows\System32\new*") }

Message at the side of the screen says I can't add images so this just became interesting...

    PS C:\Temp> $ErrorActionPreference = "Stop"
    PS C:\Temp> TRY { $ErrorActionPreference = "Stop"
    >>   New-Item -Type File $("C:\Windows\System32\NewFile.Txt") -ErrorAction Stop }
    >> CATCH [System.UnauthorizedAccessException],[System.UnauthorizedAccessException] { Write "Rerun with elevated permissions" }
    >> FINALLY { Get-ChildItem $("C:\Windows\System32\new*") }
    >>  

        Directory: C:\Windows\System32  


    Mode                LastWriteTime     Length Name  
    ----                -------------     ------ ----  
    -a---         7/13/2009   9:41 PM     313856 newdev.dll  
    -a---         7/13/2009   9:39 PM      76288 newdev.exe  
    New-Item : Access to the path 'C:\Windows\System32\NewFile.Txt' is denied.
    At line:2 char:15  
    +       New-Item <<<<  -Type File $("C:\Windows\System32\NewFile.Txt") -ErrorAction Stop }  
        + CategoryInfo          : PermissionDenied: (C:\Windows\System32\NewFile.Txt:String) [New-Item], UnauthorizedAccessException  
        + FullyQualifiedErrorId : NewItemUnauthorizedAccessError,Microsoft.PowerShell.Commands.NewItemCommand  

Anyway, on Computers "B" & "C" which are PSV3/PSV4 respectively, it works as expected giving the following

    PS C:\temp> `$ErrorActionPreference = "Stop"`  
    PS C:\temp> `TRY { $ErrorActionPreference = "Stop"`  
    >>   `New-Item -Type File $("C:\Windows\System32\NewFile.Txt") -ErrorAction Stop }`  
    >> `CATCH [System.UnauthorizedAccessException],[System.UnauthorizedAccessException] { Write "Rerun with elevated permissions" }`  
    >> `FINALLY { Get-ChildItem $("C:\Windows\System32\new*") }`  
    >>  
    Rerun with elevated permissions  


       Directory: C:\Windows\System32  


    Mode                LastWriteTime     Length Name  
    ----                -------------     ------ ----  
    -a---         7/13/2009   9:41 PM     313856 newdev.dll  
    -a---         7/13/2009   9:39 PM      76288 newdev.exe  


    PS C:\temp>  

As you can see in the source code above. The $ErrorActionPreference line is there outside the try block as well as inside the try block in addition to the -Erroraction Stop on the command itself, and on the V2 computers it isn't working, while the V3/V4 machines it is.

Better than 98% of the machines are PSv2 and for reasons no one has yet shared we are not allowed to upgrade them.

Any thoughts or ideas are welcome. Thank you,

Answer 1

The only thing that stands out to me is that you are using the "Write" shorthand instead of the full "Write-Host" command in your script. I would expect that this might cause an issue because there are a number of different "Write-*" commands that you can execute in PowerShell. It may be that V3 and V4 of PowerShell has "Write" as a short-hand for "Write-Host", whereas V2 does not.

Here's an updated example of your code just for clarity;

$ErrorActionPreference = "Stop"
TRY { New-Item -Type File $("C:\Windows\System32\NewFile.Txt") }
CATCH [System.UnauthorizedAccessException]
{ Write "Rerun with elevated permissions" }
FINALLY { Get-ChildItem $("C:\Windows\System32\new*") }

I've also removed the unnecessary ErrorAction information - based on the code you've written, the $ErrorActionPreference only needs setting once, as the UnauthorizedAccessException will generate a terminating error if the preference is set outide of the Try/Catch/Finally block. Additionally, you should only need one instance of the [System.UnauthorizedAccessException] block next to Catch for this to work.

Hope this helps!