Api request returns "unauthorized" or fails in general

a. Make sure your consumer token and token secret are correct. These are retrieved from your Twitter App's config at http://dev.twitter.com.

b. If on Android, make sure you are using API SDKs, so APIs 1.6, APIs 2.2, APIs X.X.

c. Make sure the system time is correct, see this post: http://blainegarrett.com/2009/07/14/failed-to-validate-oauth-signature-and-token-on-twitter-oauth-check-your-cloc/

If it is not one of these be sure to post an issue ticket with the output from using the debug branch, and make sure you remove any sensitive data, such as your keys.