When I do ANYTHING with gradle in Windows 10, it gives me the same error. Keep in mind I changed NOTHING before upgrading and it was working on windows 8.
https://gyazo.com/d3862e3351a5faaea1d622f20687cbeb
As you can see, I have all the correct files, and have tried reinstalling jdk and jre, along with creating new forgemodding folders and testing...help???
HOWEVER, I can still run the mod through eclipse and it works.
EDIT: I just build the project on my spare mac, and it worked, so the error isn't with the code, I believe.