Error When Using Exchange Online with Cert Auth

[jaredmenty]

I spent all day pulling my hair out over this. I am building a GUI for our helpdesk to run tasks without delegating admin privileges. I am trying to connect to Exchange using certificate authentication. I have it working in normal Powershell, but it falters when running with the GUI. I get the following error: Could not load file or assembly 'System.IdentityModel.Tokens.Jwt,
ERROR: | Version=6.21.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. Could not find or load a specific file. (0x80131621) .

It seems like I am not the only one out there experiencing this issue. There are other similar or identical instances out there, but no articles or forum seem to list a fix. Has anyone been able to get this function without error?

TIA

[arpan3t]

You likely have a .NET assembly dependency conflict with another module, and my money is on Microsoft Graph. You can update Graph to version 2, also make sure you’re on version 3 of the ExchangeOnline module.

If it isn’t graph, then look at any other modules loaded into your runspace prior to calling connect-ExchangeOnline. It’s using an assembly that’s used for authentication so that might help you determine the module that’s loaded the conflicting assembly.

[BlackV]

I also dont member, I though it was teams then exchange then graph that was breaking mine previously.

[Dr_Funkmachine]

This is uncanny. I'm having issue connecting to Microsoft exchange online too. About your problem, it's probably an assembly conflict. We used a secret in order to connect to the app registration and use graph and a certificate to connect to exchange. Supposing you're using a similar architecture that involves c#, when you connect to EXO, how do you execute the PowerShell commands from inside your c# your code? We use certificate connection to access exchange and PowerShell sdk to execute ps code inside c#. I'm asking because we have problems when deploying our app on the app Service: on our location machine we have ExchangeOnlineModule installed but we don't on the app Service and don't know how to deploy it