I have a similar issue in that after loading MiniProfiler and MiniProfiler.EnitiyFramework6 I have this issue. MiniProfiler runs fine, but when I add to my Applcation_Start
For others having similar issues This is how I resolved
Please analyze what version of Entity Framework your application is using PM> Get-Package
and then install MiniProfiler.EF accordingly
Like in my case I installed Install-Package MiniProfiler.EF5