Unable to authorize for slack integration

[karandesai28]

Steps to reproduce:

1. Go to: https://promactslack.azurewebsites.net
2. Click on "Log in with promact"
3. Enter credentials received in mail and login
4. Click on Yes allow on screen that opens up after login
5. It does not authorize and gives "An Error has occurred while processing your request" message on screen appears (attached screenshot)