Android Studio: Task '-' not found in root project '[Project Name]' after speeding up build

Question

I have been trying to speed up the gradle build time in Android Studio, and now whenever I Build or Sync my project I get the error:

Error:FAILURE: Build failed with an exception.

* What went wrong:
Task '-' not found in root project '[Project Name]'.

* Try:
Run gradle tasks to get a list of available tasks. Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

After days of googling, I have not found anything. Does anyone know what may have caused this error, I cannot test my project now.

Every other question does not specify the task '-', but something else.

I have supplemented in "[Project Name]" for the actual project name.

My project build.gradle is:

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.1.3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

And my module build.gradle is:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23"

    defaultConfig {
        applicationId "ca.lakeeffect.scoutingapp"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.0.0'
}

And my gradle.properties:

# Project-wide Gradle settings.

# IDE (e.g. Android Studio) users:
# Gradle settings configured through the IDE *will override*
# any settings specified in this file.

# For more details on how to configure your build environment visit
# http://www.gradle.org/docs/current/userguide/build_environment.html

# Specifies the JVM arguments used for the daemon process.
# The setting is particularly useful for tweaking memory settings.
# Default value: -Xmx10248m -XX:MaxPermSize=256m
# org.gradle.j# Project-wide Gradle settings.

# IDE (e.g. Android Studio) users:
# Settings specified in this file will override any Gradle settings
# configured through the IDE.

# For more details on how to configure your build environment visit
# http://www.gradle.org/docs/current/userguide/build_environment.html

# The Gradle daemon aims to improve the startup and execution time of Gradle.
# When set to true the Gradle daemon is to run the build.
# TODO: disable daemon on CI, since builds should be clean and reliable on servers
org.gradle.daemon=true

# Specifies the JVM arguments used for the daemon process.
# The setting is particularly useful for tweaking memory settings.
# Default value: -Xmx10248m -XX:MaxPermSize=256m
org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

# When configured, Gradle will run in incubating parallel mode.
# This option should only be used with decoupled projects. More details, visit
# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
org.gradle.parallel=true

# Enables new incubating mode that makes Gradle selective when configuring projects.
# Only relevant projects are configured which results in faster builds for large multi-projects.
# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:configuration_on_demand
org.gradle.configureondemand=truevmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

# When configured, Gradle will run in incubating parallel mode.
# This option should only be used with decoupled projects. More details, visit
# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
# org.gradle.parallel=true

Answer 1

I didn't know what to do, so as a last resort, I made a new project and copied over my code. I then hit File > Restart and rebuilt my project a couple of times. That worked! If anyone else finds the real answer that would be awesome to know.