Author Posts

July 19, 2018 at 8:08 am

Hello!

I have the next PowerShell script:

…
[System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms");
…
function f
{
  ….
  try {
     …
  }
  catch {
     [System.Windows.Forms.MessageBox]::Show("Error: $_", "Error","OK","Error");
  }

}

…

When I run this script from PowerShell ISE – all works fine, but in PowerShell console I get the error:
[System.Windows.Forms.MessageBox]::Show("Error...
Unable to find type [System.Windows.Forms.MessageBox]

I have tried to add to my script 'Add-Type -AssemblyName System.Windows.Forms', but it didn't give effect – I still get previous error.
When I enter in PowerShell console 'Add-Type -AssemblyName System.Windows.Forms' before running the my scripts – all also works fine, but it's not decision. Script must run correctly without any preparations.

July 19, 2018 at 12:29 pm

From what I can see of the script, this should be fine (although that semicolon is unnecessary).

One alternative you can try is:

Add-Type -AssemblyName PresentationFramework

[System.Windows.MessageBox]::Show("Error: $_", "Error", "OK", "Error")

July 19, 2018 at 4:47 pm

One refinement. On my computer with Windows 10 and PowerShell Version 5.1.17134.165 all works fine when I start script from PowerShell console, but on Windows Server 2012 with PowerShell Version 5.1.14409.1012 I still get the previous error.
Bruce Payette wrote in "Windows PowerShell in Action" about 'using assembly' operator:
"There was a bug in how using assembly worked; instead of scanning the assembly before it's
loaded, it defers loading it until runtime. This, unfortunately, makes it exactly useless for its
intended purpose. Hopefully that bug will be fixed by the time you read this, but if not and you
see a “type not found” error, at least you'll know why."
I think I face this bug in my script in not last PowerShell version