Powershell unable to find type [System.Windows.Forms.KeyEventHandler]

user4317867 picture user4317867 · Jan 6, 2015 · Viewed 28k times · Source

This might be a pretty simple question but I'm totally lost and searching for an answer hasn't been helpful.

I've got some powershell code to display a simple GUI with TextBoxes. Some of the textboxes allows the user to press Enter to run Button_Click code. When I try running the PS1 script, I get errors saying the following:

Unable to find type [System.Windows.Forms.KeyEventHandler].
Make sure that the assembly that contains this type is loaded.At C:\Scripts\GUI-Testing.ps1:161 char:1

$TestVar=[System.Windows.Forms.KeyEventHandler]
CategoryInfo          : InvalidOperation: (System.Windows.Forms.KeyEventHandler:TypeName)
FullyQualifiedErrorId : TypeNotFound

The strange part, if I close the GUI then re-run the script, I don't get the Unable to find type error and pressing Enter works as desired.

Thinking I had an answer, I tried using [void][reflection.assembly]::Load('System.Windows.Forms.KeyEventHandler') which give this error Exception calling "Load" with "1" argument(s): "Could not load file or assembly 'System.Windows.Forms.KeyEventHandler' or one of its dependencies. [FileNotFoundException]

Answer

Frédéric Bégin picture Frédéric Bégin · Jan 6, 2015

Make sure you load the following assemblies at the top of your script:

[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing") 
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") 

If it's still not working, you could do something like:

$objForm.KeyPreview = $True
$objForm.Add_KeyDown({
    if ($_.KeyCode -eq "Enter") 
    {    
        #Write Code Here
    }
})