Exchange – Application cannot be started when installing Exchange Online PowerShell Module

We’ve recently enforced MFA for admin accounts that connect to Exchange (and other O365 Services). This means that in order to connect via PowerShell we need to install the Exchange Online PowerShell module.

Instructions provided by Microsoft can be found here:

However, when I tried to install the module I kept receiving the error “Application cannot be started. Contact the application vendor“.

A quick Google shows that this seems to be a common problem. I tried the usual fixes which included using the Edge/IE browser to download the application. Though this still resulted in the same error.

Opening the error log, I can see that it’s complaining that “Deployment and application do not have matching security zones“.

After a bit of trial and error it looks like we need to modify a registry entry.


  • Open Registry Editor – Win + R keys > Type – regedit > Press Enter.
  • Go to – Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft.NETFramework\Security\TrustManager\PromptingLevel
  • Edit the Internet value and replace Disabled with Enabled.
  • Now download the application again and try to install it.
    • It should now install and open a new PowerShell console with the module loaded!
    • If you still get the same error, try using a different browser (like Edge).

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