forgegradle error: Inherited json file (1.12.2) not found! Maybe you are running in offline mode?

full crash log:

10:15:39: Executing task 'setupDecompWorkspace'...

> Configure project :
This mapping 'snapshot_20171003' was designed for MC 1.12! Use at your own peril.
C:\Users\angel\.gradle\caches\minecraft\net\minecraftforge\forge\1.12.2-14.23.5.2768\userdev\dev.json could not be parsed

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'lava_hack'.
> java.io.FileNotFoundException: Inherited json file (1.12.2) not found! Maybe you are running in offline mode?

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/4.9/userguide/command_line_interface.html#sec:command_line_warnings

BUILD FAILED in 0s
10:15:40: Task execution finished 'setupDecompWorkspace'.