.NET Application Errors with Status 500 from POST/callback

Problem statement

After successful authentication, the application throws an error with status code 500 when Auth0 sends the response to the application’s callback URL.

The following are in use:

  • Net6 Web OpenId
  • AspNetCore

Symptoms

After successful authentication, the application throws an error with status code 500 when auth0 sends the response to the application’s callback URL.

Cause

A required application cookie may be missing in the form post request to the /callback URL

Solution

One way to solve this is to simply restart the server. Turning it off and on again previously proved to solve the problem.

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