How to fix DLL LoaderExceptions in PowerShell - powershell

Question

I'm trying to load a .dll of itext7, but if I use this
Add-Type -Path "D:\Eigene\Packages\itext7.7.1.5\lib\net40\itext.kernel.dll"
I get the following exception (translated from german):
Add-Type : Add-Type : Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
In Zeile:2 Zeichen:1
+ Add-Type -Path "D:\Eigene\Packages\itext7.7.1.5\lib\net40\itext.kerne ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Add-Type], ReflectionTypeLoadException
+ FullyQualifiedErrorId : System.Reflection.ReflectionTypeLoadException,Microsoft.PowerShell.Commands.AddTypeCommand
When I use:
try { Add-Type -Path "D:\Eigene\Packages\itext7.7.1.5\lib\net40\itext.kernel.dll" }
catch { $_.Exception.LoaderExceptions }
It says (also translated from german):
The File or Assembly "BouncyCastle.Crypto, Version=1.8.1.0,
Culture=neutral, PublicKeyToken=0e99375e54769942" or a dependency of
it was not found. The system can not find the specified file.
How can I fix this?
EDIT:
I found a BouncyCastle dll on my system that it also downloaded when I installed the itext7 package but it also doesn't work, if I load "D:\Eigene\Packages\Portable.BouncyCastle.1.8.5\lib\net40\BouncyCastle.Crypto.dll" before i load the itext.kernel.dll.

Answer 1

Your assembly is looking for a different version than you have.
I'm not sure if you can do an assembly binding in powershell like you could with an application where you could bind an older assembly to a new one example:
https://learn.microsoft.com/en-us/dotnet/framework/deployment/configuring-assembly-binding-redirection
Your error is asking you to load the dll of version 1.8.1.0 with the public token of: PublicKeyToken=0e99375e54769942
Generally the assembly publisher isn't changing their public token although it is technically possible bouncy castle could so you likely don't need to specify that.
Anyway you need to find the older version (seems like you have 1.8.5). It is likely these are compatible, but best / safest bet is to use the same assembly the one you are loading needs.
You may find some help here if you need to do binding redirection to the newer assembly: Powershell - Assembly binding redirect NOT found in application configuration file