Fixed: Waiting for the .Net 4.8 installer to finish before continuing

 Today I got to the bottom of a tough one.  My customer is building 2019 servers from a template, but they are getting a weird error when trying to update.  It looks like the update is installing, but it never shows as installed.

Skip ahead A LOT of troubleshooting and today I figured out that the .net Framework 4.8 installer does not block a script while it's installing.  It immediately returns to the script. 

The fix is to force PowerShell to wait for it to finish.  Instead of just calling the installer, run this instead.

$installer = [System.Diagnostics.Process]::Start( "z:\ndp48-x86-x64-allos-enu.exe",'/q /norestart /log "%WINDIR%\Temp\DotNET48Installer.log"')

$installer.WaitForExit()

This would have gone SIGNIFICANTLY faster if the customer had shared the full build process scripts with me instead of just working through a screen share.  It was 100% reproducible, but I never got the script that had the bug in it. :/