[1.12.2] Updating Workspace failed

Recently, I decided to update my version of Forge for use in Eclipse, by updating to the recommended version. I installed the MDK, dropped everything on in, Shift Right-click opened CMD, and attempted to run 'gradlew setupDecompWorkspace'. Only for the following failure:

FAILURE: Build failed with an exception.

* What went wrong:
Could not resolve all dependencies for configuration ':forgeGradleUserDevPackage'.
> Could not resolve net.minecraftforge:forge:1.12.2-14.23.5.2768.
  Required by:
      com.yourname.modid:ModName:1.0
   > Could not resolve net.minecraftforge:forge:1.12.2-14.23.5.2768.
      > Could not get resource 'https://files.minecraftforge.net/maven/net/minecraftforge/forge/1.12.2-14.23.5.2768/forge-1.12.2-14.23.5.2768.pom'.
         > Could not GET 'https://files.minecraftforge.net/maven/net/minecraftforge/forge/1.12.2-14.23.5.2768/forge-1.12.2-14.23.5.2768.pom'.
            > sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

I have already tried rebooting my PC, and googling this report, to no avail. Absolutely any help would be appreciated.