Hey,

It looks like you mix different versions of GHC. As you said before - `ghc-mod` is build with `GHC-7.8.4`. But in the quoted error I see `ghc-7.10.3`. You have to reinstall `ghc-mod` with GHC you are using in project. 

You can find more info here: https://github.com/syl20bnr/spacemacs/issues/5674#issuecomment-206440654