No value has been specified for property mainClassName

[nogo]

Please check the (User Guide)[http://imperceptiblethoughts.com/shadow] before submitting "how do I do 'x'?" questions!

Shadow Version

2.0.1

Gradle Version

4.3

Expected Behavior

work as in 4.2.1

Actual Behavior

:shadowJar
A problem was found with the configuration of task ':shadowJar'. Registering invalid inputs and outputs via TaskInputs and TaskOutputs methods has been deprecated and is scheduled to be removed in Gradle 5.0.

• No value has been specified for property 'mainClassName'.

Build script

Extract of my build script

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'com.github.johnrengelman.shadow'

mainClassName = 'com.package.to.Class'

shadowJar {
baseName = 'launcher'
classifier = null
version = null
}

[andrii-kovalenko-ct]

same here, just have updated to gradle 4.3, shadow version 2.0.1 (as before)

[schnapster]

Fwiw the resulting jar still works (for me) despite the warning, what actually breaks with gradle 4.3 is runShadow.

[lbergelson]

I'm also seeing this with shadow 2.0.2 and gradle 4.4.

[sgnewson]

Might just be a missing mainClassName = 'com.package.to.Class' in this plugin's build?

[jonwagner]

If you define mainClassName before you apply the plugin, the build succeeds. Sounds like an issue with initialization order.

[sgnewson]

Can confirm, placing the mainClassName after the application plugin and before the shadow plugin lines removes the warnings

[Mat2095]

I'm also seeing this with shadow 2.0.2 and gradle 4.5.

[johnrengelman]

yeah, i need to improve this, but the workaround is to specify mainClassName before applying the Shadow plugin.

[RaviH]

With the build.gradle below, I still get:

A problem was found with the configuration of task ':vertx-web:shadowJar'. Registering invalid inputs and outputs via TaskInputs and TaskOutputs methods has been deprecated and is scheduled to be removed in Gradle 5.0.
- No value has been specified for property 'mainClassName'.
The SimpleWorkResult type has been deprecated and is scheduled to be removed in Gradle 5.0. Please use WorkResults.didWork() instead.

> Task :vertx-web:startShadowScripts 
Using TaskInputs.file() with something that doesn't resolve to a File object has been deprecated and is scheduled to be removed in Gradle 5.0. Use TaskInputs.files() instead.

Gradle version: 4.4

plugins {
    id 'application'
    id 'com.github.johnrengelman.shadow' version '2.0.1'
}

mainClassName = 'io.vertx.core.Launcher'
def vertxVersion = '3.5.0'
def mainVerticleName = 'com.charter.devtool.web.vertx.verticle.MainVerticle'
def watchForChange = 'src/**/*'
def doOnChange = './gradlew classes'

dependencies {
    compile project(':devtool-core')
    compile project(':devtool-db')
    compile project(':devtool-stash-client')

    compile('io.vertx:vertx-core:3.5.0')
    compile('io.vertx:vertx-web:3.5.0')
    compile('com.zandero:rest.vertx:0.7.5')
    compile('org.eclipse.jgit:org.eclipse.jgit:4.9.2.201712150930-r')
    compile('com.github.salomonbrys.kodein:kodein:4.1.0')
}

shadowJar {
    mainClassName = 'io.vertx.core.Launcher'
    classifier = 'fat'
    manifest {
        attributes "Main-Verticle": mainVerticleName
    }
    mergeServiceFiles {
        include 'META-INF/services/io.vertx.core.spi.VerticleFactory'
    }
}

run {
    args = ['run', mainVerticleName, "--redeploy=$watchForChange", "--launcher-class=$mainClassName", "--on-redeploy=$doOnChange"]
}

[Mat2095]

Try something like

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:2.0.2'
    }
}

plugins {
    id "application"
}

mainClassName = '...'

apply plugin: 'com.github.johnrengelman.shadow'

[...]

[ljohnston]

The above workaround fixes the 'mainClassName' issue, but does not address the following warning:

Task :vertx-web:startShadowScripts
Using TaskInputs.file() with something that doesn't resolve to a File object has been deprecated and is scheduled to be removed in Gradle 5.0. Use TaskInputs.files() instead.

[ljohnston]

After a little more digging, seems like this has been fixed but not yet released. Thx @johnrengelman ! Looking forward to 2.0.3.

[koralgooll]

The application plugin needs this property in gradle build file. It is in docs.

[abcfy2]

shadow plugin 2.0.3 with gradle 4.6 still have this issue:

buildscript {
    repositories {
        mavenLocal()
        maven { url "http://maven.aliyun.com/nexus/content/groups/public" }
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:2.0.3'
    }
}

apply plugin: 'codenarc'
apply plugin: 'groovy'
apply plugin: 'maven'
apply plugin: 'application'
apply plugin: 'com.github.johnrengelman.shadow'
apply plugin: 'idea'

mainClassName='com.zcwl.BarnApplication'

./gradlew shadowjar --warning-mode=all

> Task :shadowJar 
A problem was found with the configuration of task ':shadowJar'. Registering invalid inputs and outputs via TaskInputs and TaskOutputs methods has been deprecated and is scheduled to be removed in Gradle 5.0.
 - No value has been specified for property 'mainClassName'.


BUILD SUCCESSFUL in 6s
5 actionable tasks: 3 executed, 2 up-to-date

[hpmtissera]

Looks like issue is fixed in Version 2.0.4

[Mat2095]

I'm still getting the error with version 2.0.4.

[maikelsteneker]

The problem is still there for me when using 2.0.4 as well.

[RichyHBM]

Has there been any progress on this @johnrengelman ?

[black-snow]

Moving mainClassName before applying the plugin doesn't help for me.

[takirala]

This is still a problem with gradle 4.10 and shadow 2.0.4.

[sora4222]

For those that are having a struggle in Intellij and their Gradle build, please check your gradle build in gradle/wrapper/graddle-wrapper.jar
I was having this issue until I changed my gradle version to 4.9, I actually did this by just changing the referenced gradle file to */gradle-4.9-bin.zip. 4.9 solved it for me.

[takirala]

@sora4222 When you say solved do you mean that the warning no longer appears or were you able to compile the code ?

I am using gradle 4.10 and the warning still appears for me with 2.0.4

[maikelsteneker]

No longer an issue for me using Gradle 4.4 and shadow 4.0.1.

[sasconsul]

I have the problem with shadow plugin version 4.0.3, dropping back to 4.0.2 works.

[yinxing2008]

update to shadow plugin version 5.0.0

[lUNuXl]

$ ./gradlew --version

------------------------------------------------------------
Gradle 5.6.2
------------------------------------------------------------

Build time:   2019-09-05 16:13:54 UTC
Revision:     55a5e53d855db8fc7b0e494412fc624051a8e781

Kotlin:       1.3.41
Groovy:       2.5.4
Ant:          Apache Ant(TM) version 1.9.14 compiled on March 12 2019
JVM:          1.8.0_242 (Oracle Corporation 25.242-b08)
OS:           Linux 4.19.107-2-lts amd64

buildscript {
    repositories {
        jcenter()
    }
    
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.github.jengelman.gradle.plugins:shadow:2.0.4'
    }
}

apply plugin: 'com.github.johnrengelman.shadow'
apply plugin: 'kotlin'
apply plugin: 'application'

mainClassName = "io.ktor.server.jetty.EngineMain"
group 'pl.smiesznadomena'
version '0.0.2'


sourceSets {
    main.kotlin.srcDirs = main.java.srcDirs = ['src']
    test.kotlin.srcDirs = test.java.srcDirs = ['test']
    main.resources.srcDirs = ['resources']
    test.resources.srcDirs = ['testresources']
}

repositories {
    mavenLocal()
    jcenter()
    maven { url 'https://kotlin.bintray.com/ktor' }
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
    implementation "io.ktor:ktor-server-jetty:$ktor_version"
    implementation "ch.qos.logback:logback-classic:$logback_version"
    implementation "io.ktor:ktor-server-core:$ktor_version"
    implementation "io.ktor:ktor-server-host-common:$ktor_version"
    implementation "io.ktor:ktor-locations:$ktor_version"
    testImplementation "io.ktor:ktor-server-tests:$ktor_version"
    implementation 'net.dv8tion:JDA:4.1.1_133'
}

// This task will generate your fat JAR and put it in the ./build/libs/ directory
shadowJar {
    manifest {
        attributes 'Main-Class': mainClassName
    }
}

A problem was found with the configuration of task ':shadowJar'.
> No value has been specified for property 'mainClassName'.

[jsonwan]

I have the problem with shadow plugin version 2.0.2 and gradle version 6.1.0, upgrade shadow plugin to 5.1.0 works.

[eric-ampire]

I have the same problem but I solved it by updating Gradle to version 6.1.1 and I also updated the version of shadow classpath "com.github.jengelman.gradle.plugins:shadow:6.0.0".

[red-avtovo]

In order to fix the issue you need to add the following block in build.gradle:

application {
	// Desired way mainClass.set("<main class>") causes an issue during jar packaging
	@Suppress("DEPRECATION")
	mainClassName ="<your main class here>"
}

[vojkny]

        // Desired way mainClass.set("<main class>") causes an issue during jar packaging
	@Suppress("DEPRECATION")
	mainClassName ="<your main class here>"

This is not a solution - the mainClassName should not be used anymore, so the shadow plugin should not use it.

[joffrey-bion]

@knyttl for this reason I believe the issue should be reopened. This is a bug in the shadow plugin, using a deprecated API, and it should be fixed.

I'm surprised on Gradle side, though, that calling mainClass.set("...") doesn't also set mainClassName for backwards compat.

EDIT: my bad, I just noticed that this is tracked here already: #609

[pmorch]

This solution doesn't work with gradle 6.7 and shadowJar 6.1.0:

application {
	// Desired way mainClass.set("<main class>") causes an issue during jar packaging
	@Suppress("DEPRECATION")
	mainClassName ="<your main class here>"
}

It removes the strikethrough formatting from Intellij, but ./gradlew shadowJar still reports:

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.7/userguide/command_line_interface.html#sec:command_line_warnings

And it sounds like suppression of warnings from gradle is not possible by choice...

[jspetrak]

This solution doesn't work with gradle 6.7 and shadowJar 6.1.0:

And it sounds like suppression of warnings from gradle is not possible by choice...

@pmorch I have just had the same issue on Gradle 7.0 and ShadowJar 6.1.0... After gradle clean build shadowJar the error did not occur.