Using Unity 2020.1 OSX - Mojave VS 8.7 All the rest is standard. I know this has been already discussed, but I could not solve the problem. I have some scripts that need unsafe code, but every time I end up migrating to a new system something goes wrong and I start getting this error: error CS0103: The name 'Unsafe' does not exist.. Last time I solved doing a fresh project, since all the work around didn't work for me. But now I got sucked again and the project got too big to easily migrate. Already checked the "unsafe code" option in the player in unity. Also tried the solutions involving creating the files: smcs.rsp file to csc.rsp, or gmcs.rsp . It didn't work and I also don 't get why this should help. Deleting the library folder also didn't help. Someone could tell me how to solve the problem, possibly explaining how do things work?