I had a class: public class Constant { public static string ConnString = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString; } which would throw exception on LIVE: Type initialize failed for Constant ctor If I change the class to: public class Constant { public static string ConnString { get { return ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString; } } } it works. I wasted 2 hours behind this but I still don't know why would this happen. Any ideas? Note: The 1st class used to work on DEV environment but not on LIVE. The 2nd class works on DEV and also on Production. I am using VS2010 on production and Asp.Net 4.0 Website project. I am totally amazed by this inconsistency to say the least! Edit: This class was in App_Code folder.