Compiler errors (CS0246 & CS0234)

Hi, I had my project working in play mode on Unity, but when I tried to build it as exe, all of sudden, a lot of compiler errors showed up and the project stopped working. Now Unity doesn't even allow me to enter the play mode and says I need to fix all the errors first.

I'm sure that t$$anonymous$$s is not a network problem (I've tested to build on a different network but got the same result), and all the errors seemed to be related with my assets (VRTK, Oculus Utilities & Avatar, ETC.) There are only two error types: CS0234 and CS0246. Does anyone know how to fix t$$anonymous$$s?

Thanks for your help in advance.