Last modified: 2014-10-06 12:36:32 UTC
Since the new serialization format I can't get 500 items at a time. I get HTTP/1.1 503 Service Unavailable. It works with 400 at this time.
Which request are you making exactly? Is this via the API? Or Special:Export? Or something else?
(In reply to Lydia Pintscher from comment #1) wbgetentities via the API. All entities were updated previously.