botbuilder-js: [OAuthPrompt] The call to https://api.botframework.com/api/usertoken/GetToken returns a 500 response

Versions

4.16

Describe the bug

When using the OAuthPrompt Dialog from the SDK, the call to https://api.botframework.com/api/usertoken/GetToken performed by the SDK returns a 500 status error response. According to the code, the SDK awaits either a 200 or 404 status.

To Reproduce

Steps to reproduce the behavior:

I tried to follow this guide in order to add authentication to the bot with my own identity provider:

https://learn.microsoft.com/en-us/azure/bot-service/bot-builder-authentication?view=azure-bot-service-4.0&tabs=userassigned%2Caadv2%2Ccsharp

1. Configure a custom identity provider on Azure
2. Configure the bot with the identity provider connection name
3. Type anything
4. Auth Prompt should appear but nothing happens
5. I receive a 500 status code in the response
6. The bot console displays the following error:

      body: '{\r\n' +
        '  "error": {\r\n' +
        '    "code": "ServiceError",\r\n' +
        '    "message": "Error retrieving token: caeb276526109146868df38d74c9c52a."\r\n' +
        '  }\r\n' +
        '}',

Expected behavior

Auth Prompt should display a sign-in button