redirect_uri differs between sign-in and token exchange

What it means

The token request must send the identical redirect_uri used in the authorization request.

Use one exact string in both requests (your app may be normalising it, e.g. adding a slash).

Run your login and smart-doctor ranks this cause against the others, with the evidence it found.

npx smart-doctor check my-profile

Already have the server’s error? Explain it without running anything.

npx smart-doctor explain '{"error":"invalid_grant"}'