How do I set a redirect URL for login with PayPal?
All parts of the specified redirect_uri, including the protocol, host, port, and context path, must match your registered return URL. You can find your return URL on the My Apps & Credentials page after logging in to the PayPal Developer Portal.
Redirect_uri failure occurs due to an inconsistency between the account and code. If you make any changes, be sure to apply the same updates in your account and code. It may take a few hours for values to update.