This is a problem which can occur when there is an old version of a DLL still lingering somewhere around.
Make sure that the latest assemblies are deployed and no duplicated older assemblies are hiding in certain folders.
Your best bet would be to delete every built item and rebuild/redeploy the entire solution.
http://stackoverflow.com/questions/8058832/system-missingmethodexception-method-not-found
錯誤原因：項目引用的dll版本不對導致的
你好