I am working on a new LWA 'button' in my ecommerce app for web browseer. At this point, a user can click the button to login to Amazon and I get the usual Amazon login screen. Once logged in I am presented with the "Click 'Allow' to Sign-In to Sophio." When I click that button to approve, Amazon OAUTH calls my server with a 'code'. When I try to send that code back to Amazon to get an access_token I get the 500 error.
It's worth mentioning, that I am getting an access token with status=null immediately after the first step (logging in to Amazon at my callback). The doc's do not suggest that this is what will happen, so maybe my initial page is setup incorrectly?
Perhaps you can try it here - https://michael.sophio.com/amazonlogin.wws