SebS
SebS

Reputation: 591

Why am I getting Unsupported major.minor version 51.0

I am trying to compile a basic skeleton of Spring Boot 1.3.6.RELEASE application with Gradle 2.14.1. I need to use Java 6. I can't upgrade to Java 7 or 8.

Why am I getting a failed gradle build with

Unsupported major.minor version 51.0

The exception seems to be pointing to the line

apply plugin: 'spring-boot'

My gradle.properties file contains:

org.gradle.java.home=C:/Program Files/Java/jdk1.6.0_45

I have tried to include the following to use Tomcat 7 instead of Tomcat 8 but this did not help.

configurations.all {
    resolutionStrategy {
        eachDependency {
            if (it.requested.group == 'org.apache.tomcat.embed') {
                it.useVersion '7.0.56'
            }
        }
    }
} 

I have followed recomendations in spring boot refrence guide relating to Java 6 ie. to use tomcat 7 instead of 8. I am not using JTA.

* Exception is:
org.gradle.api.GradleScriptException: A problem occurred evaluating root project 'myProject'.
        at org.gradle.groovy.scripts.internal.DefaultScriptRunnerFactory$ScriptRunnerImpl.run(DefaultScriptRunnerFactory
.java:93)
        at org.gradle.configuration.DefaultScriptPluginFactory$ScriptPluginImpl$2.run(DefaultScriptPluginFactory.java:17
7)
        at org.gradle.configuration.ProjectScriptTarget.addConfiguration(ProjectScriptTarget.java:77)
        at org.gradle.configuration.DefaultScriptPluginFactory$ScriptPluginImpl.apply(DefaultScriptPluginFactory.java:18
2)
        at org.gradle.configuration.project.BuildScriptProcessor.execute(BuildScriptProcessor.java:38)
        at org.gradle.configuration.project.BuildScriptProcessor.execute(BuildScriptProcessor.java:25)
        at org.gradle.configuration.project.ConfigureActionsProjectEvaluator.evaluate(ConfigureActionsProjectEvaluator.j
ava:34)
        at org.gradle.configuration.project.LifecycleProjectEvaluator.evaluate(LifecycleProjectEvaluator.java:55)
        at org.gradle.api.internal.project.AbstractProject.evaluate(AbstractProject.java:540)
        at org.gradle.api.internal.project.AbstractProject.evaluate(AbstractProject.java:93)
        at org.gradle.execution.TaskPathProjectEvaluator.configureHierarchy(TaskPathProjectEvaluator.java:42)
        at org.gradle.configuration.DefaultBuildConfigurer.configure(DefaultBuildConfigurer.java:35)
        at org.gradle.initialization.DefaultGradleLauncher$2.run(DefaultGradleLauncher.java:124)
        at org.gradle.internal.Factories$1.create(Factories.java:22)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:53)
        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:121)
        at org.gradle.initialization.DefaultGradleLauncher.access$200(DefaultGradleLauncher.java:32)
        at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:98)
        at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:92)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:63)
        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:92)
        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:83)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter
.java:99)
        at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:28)
        at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:48)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:30)
        at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:81)
        at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:46)
        at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:52)
        at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:37)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:26)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.RequestStopIfSingleUsedDaemon.execute(RequestStopIfSingleUsedDaemon.ja
va:34)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:74)
        at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:72)
        at org.gradle.util.Swapper.swap(Swapper.java:38)
        at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:72)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.health.DaemonHealthTracker.execute(DaemonHealthTracker.java:40)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:60)
        at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:72)
        at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.health.HintGCAfterBuild.execute(HintGCAfterBuild.java:41)
        at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
        at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:50)

        at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:237)
        at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:54)
        at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:40)
Caused by: java.lang.UnsupportedClassVersionError: io/spring/gradle/dependencymanagement/exclusions/Exclusions : Unsuppo
rted major.minor version 51.0
        at io.spring.gradle.dependencymanagement.DependencyManagementPlugin.apply(DependencyManagementPlugin.groovy:58)
        at io.spring.gradle.dependencymanagement.DependencyManagementPlugin.apply(DependencyManagementPlugin.groovy)
        at org.gradle.api.internal.plugins.ImperativeOnlyPluginApplicator.applyImperative(ImperativeOnlyPluginApplicator
.java:35)
        at org.gradle.api.internal.plugins.RuleBasedPluginApplicator.applyImperative(RuleBasedPluginApplicator.java:43)
        at org.gradle.api.internal.plugins.DefaultPluginManager.doApply(DefaultPluginManager.java:137)
        at org.gradle.api.internal.plugins.DefaultPluginManager.addImperativePlugin(DefaultPluginManager.java:67)
        at org.gradle.api.internal.plugins.DefaultPluginManager.addImperativePlugin(DefaultPluginManager.java:73)
        at org.gradle.api.internal.plugins.DefaultPluginContainer.apply(DefaultPluginContainer.java:60)
        at org.springframework.boot.gradle.dependencymanagement.DependencyManagementPluginFeatures.apply(DependencyManag
ementPluginFeatures.java:44)
        at org.springframework.boot.gradle.SpringBootPlugin.apply(SpringBootPlugin.java:47)
        at org.springframework.boot.gradle.SpringBootPlugin.apply(SpringBootPlugin.java:38)
        at org.gradle.api.internal.plugins.ImperativeOnlyPluginApplicator.applyImperative(ImperativeOnlyPluginApplicator
.java:35)
        at org.gradle.api.internal.plugins.RuleBasedPluginApplicator.applyImperative(RuleBasedPluginApplicator.java:43)
        at org.gradle.api.internal.plugins.DefaultPluginManager.doApply(DefaultPluginManager.java:137)
        at org.gradle.api.internal.plugins.DefaultPluginManager.apply(DefaultPluginManager.java:112)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.applyType(DefaultObjectConfigurationAction.j
ava:113)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.access$200(DefaultObjectConfigurationAction.
java:36)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction$3.run(DefaultObjectConfigurationAction.java:
80)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.execute(DefaultObjectConfigurationAction.jav
a:136)
        at org.gradle.api.internal.project.AbstractPluginAware.apply(AbstractPluginAware.java:46)
        at org.gradle.api.internal.project.ProjectScript.apply(ProjectScript.java:34)
        at org.gradle.api.Script$apply$0.callCurrent(Unknown Source)
        at build_eb0vk878b797zgtn3oumoubtl.run(C:\Users\...\myProject\build.gradle:25)
        at org.gradle.groovy.scripts.internal.DefaultScriptRunnerFactory$ScriptRunnerImpl.run(DefaultScriptRunnerFactory
.java:91)
        ... 58 more

Upvotes: 0

Views: 1802

Answers (3)

Andy Wilkinson
Andy Wilkinson

Reputation: 116171

The dependency management plugin that Spring Boot's Gradle plugin uses requires Java 7. This means that you'll have to build your application with Java 7 (or later), but you'll still be able to run it using Java 6.

Upvotes: 0

abarisone
abarisone

Reputation: 3783

The error is caused by a dependency which has been compiled with Java 7, so it can't work with Java 6.

Having said that, reading from Spring Boot's documentation about system requirements, it seems that Java 6 is supported provided that you perform some additional configuration.

About embedded servlet containers compatibility, in section 79.9 How to use Java 6 you should use Tomcat 7 or Jetty 8 and this is the gradle configuration:

You can change the Tomcat version by setting the tomcat.version property:

ext['tomcat.version'] = '7.0.59'
dependencies {
    compile 'org.springframework.boot:spring-boot-starter-web'
}

Obviously, if you can, you'd better to upgrade to newer JVM versions.

Upvotes: 4

Czyzby
Czyzby

Reputation: 3139

Java 6 usage is precisely what causes the issue. It seems that one of the required libraries supports Java 7/8 at minimum - there's no workaround, you might have to migrate to a newer Java version.

Upvotes: 6

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