HTTP Error 500 (Internal Server Error) with open graph
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I created application with built in Open Graph action and object (read, article). When I click on Edit Open Graph and then I try to click on Read action link I get Server Error "Server error
The website encountered an error while retrieving https://developers.beta.facebook.com/apps/498561990169275/opengraph/action_type/197470933617653. It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this web page later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request."

what is the problem  

thank you