File is for an older version of Forge and cannot be loaded - n00b error

[Raeglyn]

I have an entirely blank mod that I have built using gradle and am now trying to test in Minecraft (by copying the gradle-built jar into the mods folder of my Minecraft installation).

However, on startup I get the following warning:

I'm certain this is a stupid error, but it's not clear to me what I need to update in the build.gradle file. This is what mine looks like currently:

buildscript {
    repositories {
        jcenter()
        maven { url = "http://files.minecraftforge.net/maven" }
        flatDir {
            dirs 'libs'
        }
    }
    dependencies {
        classpath 'net.minecraftforge.gradle:ForgeGradle:2.3-SNAPSHOT'
    }
}
apply plugin: 'net.minecraftforge.gradle.forge'
//Only edit below this line, the above code adds and enables the necessary things for Forge to be setup.


version = "1.0"
group = "com.yourname.modid" // http://maven.apache.org/guides/mini/guide-naming-conventions.html
archivesBaseName = "rosemary"

sourceCompatibility = targetCompatibility = '1.8' // Need this here so eclipse task generates correctly.
compileJava {
    sourceCompatibility = targetCompatibility = '1.8'
}

minecraft {
    version = "1.12.2-14.23.5.2768"
    runDir = "run"
    
    // the mappings can be changed at any time, and must be in the following format.
    // snapshot_YYYYMMDD   snapshot are built nightly.
    // stable_#            stables are built at the discretion of the MCP team.
    // Use non-default mappings at your own risk. they may not always work.
    // simply re-run your setup task after changing the mappings to update your workspace.
    mappings = "snapshot_20171003"
    // makeObfSourceJar = false // an Srg named sources jar is made by default. uncomment this to disable.
}

The minecraft version definitely needs to be updated (I'm running 1.15.2, and Forge version 1.15.2-forge-31.1.0), but I'm not sure where to find this snapshot thing. I assume I can't just replace the 1.12.2 with 1.15.2.

Thanks!

[Animefan8888]

10 minutes ago, Raeglyn said:

The minecraft version definitely needs to be updated (I'm running 1.15.2, and Forge version 1.15.2-forge-31.1.0), but I'm not sure where to find this snapshot thing.

Go to files.minecraftforge.net and download the latest mdk for 1.15.2 and you can follow this tutorial I have to setup a workspace. Assuming you are using eclipse.

[Draco18s]

8 hours ago, Raeglyn said:

minecraft {

    version = "1.12.2-14.23.5.2768"

This says you're targeting 1.12