Below you'll find most frequent Twitter publishing errors along with recommendations on what to do if they happen.
In all cases, if the error persists or if you are unable to figure out how to fix the problem, we are here to help, please contact support.
(#503) Service Unavailable
Recommendation
The Twitter servers are up, but are overloaded with requests. Twitter's team recommends trying the post again later (5-10 minutes should be enough).