ravendb/ravendb — pull request #562 by ldegroat (2014-08-19 13:13:18+00:00)
Title: Update CommandDataFactory.cs

You need to check if "Key" exists before trying to cast its value to a string. Key was not required in older versions.

I just upgrade from 4ab4776 to 6dce79a and I could no longer use the PUT command without a Key explicitly set to null.