I found the source of error. It isn´t compatible with EFProf (http://www.hibernatingrhinos.com/products/EFProf)
I am using MiniProfiler beta6 + MiniProfiler.EF6 beta 4 + EfProf 2.0.2233.0. When EFProf is active, MiniProfiler generates this error:
Unable to define EFProfiledDbProviderServices class of type 'ProfiledDbProviderServices'. Please check that your web.config defines a section underneath .
UPDATE (since I can´t reply anymore.....):
MiniProfiler is trying to access the Instance field/property of class ProfiledDbProviderServices. What doesn´t exists.
MiniProfiler.EF6 uses the old interception method with reflection or the new Interception/Log API?
If using the old method, maybe you need to unwrap ProviderServices in loop, until find the real one. For example in MiniProfilerEF6, WrapProviderService method. If I register MiniProfiler first, it works. The problem is, EFProf by default register it using WebActivator, what happens first