PowerShell App Deployment Toolkit - "Launching this application has been temporarily blocked..."

I am a huge fan of the PowerShell App Deployment Toolkit. It allows us to deploy or upgrade applications that require certain applications to be closed in a friendly manner. Instead of just killing a process (say, Internet Explorer) before running a Java upgrade, you can let the user know that that IE needs to be closed and let them finish any unsaved work before closing it. There are numerous other wonderful features of this utility, I encourage you to read more at the link above.

That said, we had a strange experience with a recent upgrade from Java 1.7 to 1.8. A number of users were unable to launch Internet Explorer after the upgrade. They all had this error message, which is a window from the PS App Toolkit:

A little Googling led me to this article, which suggested a registry key may be the problem, Indeed it was:

The full value of the key was wscript.exe "C:\Users\Public\PSAppDeployToolkit\AppDeployToolkit_BlockAppExecutionMessage.vbs"

Removing this registry key solved the issue. This is unexpected behavior from this utility, it typically would remove this key upon completion. Perhaps it's a bug in the current version (v3.5.0). Still, it's a problem for us, so we needed to make sure this wouldn't affect any other users.

The solution was to add a line of code in the post-installation section of Deploy-Application.ps1.

Remove-RegistryKey -Key 'HKLM:SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\iexplore.exe' -Name 'Debugger' -ContinueOnError $True

The full post-installation section is shown below:

##*===============================================
##* POST-INSTALLATION
##*===============================================
[string]$installPhase = 'Post-Installation'

## 

## Clean up IE registry key
Remove-RegistryKey -Key 'HKLM:SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\iexplore.exe' -Name 'Debugger' -ContinueOnError $True
      
## Display a message at the end of the install
Show-InstallationPrompt -Message 'Installation complete.' -ButtonRightText 'OK' -Icon Information -NoWait

This solved our issue, and clients are upgrading and working as expected.

UPDATE: We still see a handful of computers that experience this issue. We resolve it by pushing them the below PowerShell script. It also adds a registry value in a hive we often use for other things (and we use this for the detection logic in this app), then it notifies the user with a popup window that IE should be working properly.

# Delete registry key
remove-itemproperty -path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\iexplore.exe" -name Debugger

# Create and set value in Chico registry section for detection method purposes
New-ItemProperty -Path HKLM:\SOFTWARE\Chico -Name IEDebugger -PropertyType String -Value "Fixed"

# Notify user
$wshell = New-Object -ComObject Wscript.Shell
$wshell.Popup("Your Internet Explorer issue should be resolved. Please try running it again. If there are still issues, please contact ITSS at x4357.",0,"Done",0x1)