Cognito - Client is not enabled for OAuth2.0 flows

Question

I've successfully set up an AWS Cognito environment that runs on Localhost following this tutorial.

For the next step, I published the app to my external web server. I confirmed that the Cognito configuration (i.e. Client ID, Metadata Address, Region, etc) is correct. However, when I access and try to sign into the newly published public site I receive the follow error: " Client is not enabled for OAuth2.0 flows."

EDIT:

Here are my App Client Settings

I would like help with what I should look into in the AWS Cognito config or the Server config settings. The server is NOT using a load balancer. I believe the issue may lie somewhere in the Reverse Proxy or HTTPS settings.

Answer 1

I have seen this issue before. When making the request to Cognito, please take a close look at the redirect URL/ Call back URL you are specifying. If I remember correctly, I have seen this issue if you have a trailing '/' or a missing '/' in the redirect URL depending on what you have specified in the App Client Settings.

Answer 2

This also occurs when you set up Cognito using Cloudformation or AWS SAM, and forgot to enable AllowedOAuthFlowsUserPoolClient property to true.

Resources:
  FooBarUserPoolClient:
    Type: AWS::Cognito::UserPoolClient
    Properties:
      AllowedOAuthFlowsUserPoolClient: True # Set here