Following the recent series of posts on issues I have had migrating client sites from IIS6 to IIS7, one common problem I had was on sites that use the ELMAH exception handler. The full exception message is "Could not load file or assembly 'System.Data.SQLite' or one of its dependencies. An attempt was made to load a program with an incorrect format. ". Another easy fix for this one but rather than it being a config issue relating to the IIS version I believe this is more related to the move from a 32-Bit server to a 64-Bit Windows Server. To correct the issue you need to modify the advanced settings for your app pool to "Enable 32-Bit Applications".