If you get MappingException error, there are two things you should check out:
- Make sure the name of the *.hbm.xml is spelled correctly — not *.hmb.xml nor *.mbh.xml
- Make sure the Build Action property is set to “Embeded Resource.”
I learned this the hard way. First, I wrongly spelled hbm.xml and I had its Buld Action property set to “Content”. The above 2 points fixed the problem.
Credit: VerySimple, Inc