My web application follows the example in https://github.com/developerforce/Force.com-Toolkit-for-NET/tree/master/samples/WebServerOAuthFlow to initiate a traditional oauth flow. In my application, the user enters their client_id and secret and then initiates the oauth flow which opens a new browser window (window.open()) pointing to Salesforce to start the flow, the following url for example:
What I found is if the client_id was mistyped, the user is given an less than helpful
error=invalid_client_id&error_description=client%20identifier%20invalid. I can understand why it doesn't redirect to the redirect_uri since the client_id couldn't be validated. However, I was expecting a pretty Salesforce branded "There was a problem with your client id". As it is, my window is dead and my initiating application has no idea there was a problem.
Am I missing a flag that would ask salesforce to give a pretty error message?
I don't think there's any way from the source web page to know that the window.open() resulted in a 400.