How to resolve 'preflight is invalid (redirect)' or 'redirect is not allowed for a preflight request'

Question

I have followed this step to setup my server to enable CORS. https://docs.microsoft.com/en-us/aspnet/web-api/overview/security/enabling-cross-origin-requests-in-web-api

Answer 1

This happens sometimes when you try calling an https service as http, for example when you perform a request on:

'http://example.com/api/v2/tickets'

Which should be:

'https://example.com/api/v2/tickets'