Authorization URL not working V3

[KuljeetN]

I've been trying to set up an automatic creation to my app, as this: When a user is registered in my app, he is also registered in my constant contact account as a contact. The only problem I'm having is with the Authorization URL. I'm using .NET CORE Redirect(AuthUrl) and my AuthUrl in the same format as the API Docs, but I'm getting this response after redirecting:

https://api.cc.email/v3/idfed?client_id={ID}&scope=contact_data&response_type=code&redirect_uri=http...

Access to XMLHttpRequest at 'https://api.cc.email/v3/idfed?client_id={ID}&scope=contact_data&resp...' (redirected from 'https://localhost:44329/Subscriptions/RegisterNewCustomer') from origin 'https://localhost:44329' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

[KuljeetN]

https://api.cc.email/v3/idfed?client_id={ID}&scope=contact_data&response_type=code&redirect_uri=http...

Access to XMLHttpRequest at 'https://api.cc.email/v3/idfed?client_id={ID}&scope=contact_data&resp...' (redirected from 'https://localhost:44329/Subscriptions/RegisterNewCustomer') from origin 'https://localhost:44329' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

[Courtney_E]

Hello Kuljeet, 

It looks like while the format of the Authorization Request URL is correct, your redirect_uri does not match what you have set as the Redirect URI in the My Applications section of the V3 portal in your account.

In order to successfully redirect to the authorization page, those two values will need to match. Once the value is corrected, it should be able to redirect without issue.

https://v3.developer.constantcontact.com/login/index.html