I’m trying to implement Gmail OAuth authentication in my Android app but running into issues. I downloaded some sample code from a repository and added the necessary JAR files (signpost-commonshttp4-1.2.1.1.jar, signpost-core-1.2.1.1.jar, and signpost-jetty6-1.2.1.1.jar) to my project.
The problem is that when I launch my application, the Gmail authentication screen doesn’t appear at all. Instead, I just get an “Unauthorized” response status message. There are no compilation errors or crashes, but the OAuth flow simply won’t start properly.
Has anyone encountered this issue before? What could be preventing the Gmail sign-in page from loading? I’m not sure if it’s a configuration problem or if I’m missing something in the implementation. Any help would be greatly appreciated.
ya, seems like ur OAuth setup might be off. make sure you registered ur app in the Google Cloud Console and got the client ID/secret right. also, double-check that the redirect URI matches exactly what’s in the console, that’s often the culprit for unauthorized errors.
I ran into the same issue with Gmail OAuth on Android. Getting ‘Unauthorized’ without seeing the sign-in screen usually means your OAuth request is malformed or not sending properly. Since you’re using signpost, double-check that you’re setting the consumer key and secret before the authorization request. Also, make sure you’ve actually enabled the Gmail API in Google Cloud Console - I’ve seen people set up OAuth credentials but forget to activate the API itself. Check your OAuth endpoints too. You want Google’s OAuth server, not Gmail directly. If you’re testing on an emulator, it needs Google Play Services or OAuth will fail silently.
Sounds like a scope or permissions issue. Getting unauthorized without seeing the sign-in screen usually means your OAuth request isn’t reaching Google’s servers at all. I’ve hit this before with outdated signpost libraries for Gmail OAuth - those JAR files are ancient. Google killed off some OAuth flows and the newer Gmail API needs different auth patterns. Ditch signpost and use Google’s official OAuth client library for Android instead. The modern approach with GoogleSignInOptions handles auth way more reliably. Also double-check your app’s SHA-1 fingerprint is registered correctly in Google Cloud Console, especially if you’re testing on a real device.