[java] How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version

I am trying to use Notepad++ as my all-in-one tool edit, run, compile, etc.

I have JRE installed, and I have setup my path variable to the .../bin directory.

When I run my "Hello world" in Notepad++, I get this message:

java.lang.UnsupportedClassVersionError: test_hello_world :
 Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
       .........................................

I think the problem here is about versions; some versions of Java may be old or too new.

1. How do I fix it?
2. Should I install the JDK, and setup my path variable to the JDK instead of JRE?
3. What is the difference between the PATH variable in JRE or JDK?

In Eclipse, I just went to menu command Window -> Preferences -> Java -> Compiler and then set "Compiler compliance level" to 1.6.

As you know it is always good practice to have enviornment variable Java_home for jdk(Java development Kit) bin directory.

looking at your issue above this seems that JRE- runtime environment is looking for a class which is not compatible in Superset library of JDk. I would recommend have a completed package of JDK and JRE or Jboss(if required) from Oracle download source directly to avoid any such issues.

I got the same problem, and I fixed this issue by this solution on a Mac. I hope it helps someone. It's because the system doesn't know about the newer version of JDK, and it still points to the old JDK.

java.lang.UnsupportedClassVersionError happens because of a higher JDK during compile time and lower JDK during runtime.

In my case the problem occured because of different versions of Java in $JAVA_HOME and $PATH.

echo $JAVA_HOME
/usr/lib/jvm/java-7-openjdk-amd64/jre
echo $PATH
/opt/jdk/jdk1.8.0_151/bin:/usr/lib/jvm/java-7-openjdk-amd64/jre/bin:/usr/local/bin:/usr/bin:/bin

Once I updated them to be the same version of Java the problem was gone.

export JAVA_HOME=/opt/jdk/jdk1.8.0_151
export PATH=$JAVA_HOME/bin:$PATH

make sure you check Environment variables versions of java , it could be just the difference between the versions of JAVA_HOME (JDK path) and JRE_HOME (JRE path) , that cause the problem

I had the same situation but any of above tips didn't help :) In our environment we had tomcat running as a service on Windows. We installed Java 1.7 and set up JAVA_HOME on this version. Off course the sources were built on Java 1.7. Nevertheless the tomcat said that it use previous version of JVM. After a deep analized turn out that the Tomcat service installed on Windows still keeping the old value for JAVA_HOME pointing to Java 1.6. After installing new Tomcat service everything were resolved. So the conclusion is: When you change java version and tomcat running as a service, you have to reinstall tomcat service.

When I installed JDK 1.7, the problem got solved.

I had the same error message when running Ant from Eclipse, but the other solutions mentioned here didn't solve my problem. The funny thing was that running Ant from the Windows command line was running fine, so it had to be a configuration issue within Eclipse.

It turned out that under Eclipse you can specify the environment that Ant should be running with and this was set as a JRE instead of a JDK.

• Go to: Run -> External Tools -> External Tools Configurations ...
• Select the Ant build.xml for your project (if you have multiple projects)
• Activate the Tab 'JRE'
• Here was selected 'Separate JRE: jre6'. When I changed this to a JDK from the 1.6 or 1.7 series, the error was gone.

I solved it. I ran:

JAVA_HOME=/usr/lib/jvm/java-7-openjdk-i386

The error is misleading, Unsupported major.minor version 51.0. This gives the impression that version 51 (Java 7) is not supported. And we should use Java 6.

The error should have been:

The current Java version, 50, is unsupported. Use Java version 7 (51:0 and greater) instead.`

I got the same issue with Spring Source Tool (STS) IDE for a Grails project. I checked the installed Java version and the project Java version were 1.7.*. Later I found that in GGTS.ini file the Java version was set to 1.6:

Solution:

-Dosgi.requiredJavaVersion=1.6 changed to
-Dosgi.requiredJavaVersion=1.7
Add below two lines before -vmargs
-vm
jdk1.7.0_21/jre/lib/amd64/server/libjvm.so

Problem solved. Happy coding.

How do I fix it?

This error means that the JRE that is being used to execute your class code does not recognise the version of Java used. Usually because the version of Java that generated your class file (i.e. compiled it) is newer.

To fix it, you can either

a) Compile your Java sources with the same, or older, version of the Java compiler as will be used to run it. i.e. install the appropriate JDK.

b) Compile your Java sources with the newer version of the Java compiler but in compatibility mode. i.e. use the -target parameter.

c) Run your compiled classes in a JRE that is the same, or newer, version as the JDK used to compile the classes.

You can check the versions you are currently using with javac -version for the compiler, and java -version for the runtime.

Should I install the JDK, and setup my PATH variable to the JDK instead of JRE?

For compilation, certainly, install and configure the specific JDK that you want.

For runtime, you can use the one that comes with the JDK or a standalone JRE, but regardless, make sure that you have installed the right versions and that you have configured your PATH such that there are no surprises.

What is the difference between the PATH variable in JRE or JDK?

The PATH environment variable tells the command shell where to look for the command you type. When you type java, the command shell interpreter will look through all the locations specified in the PATH variable, from left to right, to find the appropriate java runtime executable to run. If you have multiple versions of Java installed - i.e. you have the java executable in multiple locations specified in the PATH variable, then the first one encountered when going from left to right will be the one that is executed.

The compiler command is javac and only comes with the JDK. The runtime command is java and comes with the JDK and is in the JRE.

It is likely that you have one version (51.0 = Java 7) of javac installed, and you also have the same version of java installed, but that another previous version of java is appearing earlier in the PATH and so is being invoked instead of the one you expect.

• If you use Maven, set your Java compile level. Open a command line and write java -version for your compile level:

  

• If you use IntelliJ IDEA, select project ? File ? Settings ? Build Execution Deployment ? Compiler ? Java Compiler. Then change byte code as 1.7 like this image:

  

Yet another way to fix this on Mac OS X with Homebrew installed, is this:

brew install Caskroom/cask/java

1. Click Properties in a project.
2. Go to Java Build Path.
3. Click Add Library.
4. Click Next on JRE System Library. Select the one you need if not selected by default.
5. Click Finish.

You're done!

You have used a higher version of the JDK to compile and trying to run from a lower version of JDK/JRE.

To check this, see the version information:

javac -version

java -version

They will be different and javac will have a higher version number.

To get around this, run using java from the JDK version or if you have a newer JRE/JDK that will work as well.

which javac will tell you the location, for example, /usr/bin/javac. Just run directly using /usr/bin/java <program>.

OR you can set the environment variable as a permanent solution.

Your Java file is compiled with a different version (higher compiler version) than the version (lower runtime version) you are trying to run it with.

It is basic understanding that classes compiled with lower versions are expected to run in the later higher versions. But the opposite (compiled with higher compiler version and trying to run it with lower runtime version) is quite not possible sometimes.

Hence you are shown this error, when trying to execute your program. Unsupported major.minor version x.x

Q: I have created an application in Java 7, but when my users try to run it they get an Unsupported major.minor version 51.0 error. What does this mean and what can I do about it?

A: If you compile an application using javac in Java 7, the resulting classfiles will have the 51.0 version number. Versions of Java prior to 7 do not recognize this number, so your users will have to upgrade to Java 7 prior to running your application. If you are not using any Java 7 APIs you can try to compile your application using javac -target 1.6 to create a 1.6-compatible classfile. If your application is deployed using webstart you can specify the minimum version required. For more information, see the docs on Java Web Start and JNLP here. This issue will go away once we trigger autoupdate to Java 7 for end-users currently having Java 6 on their desktops. The timeline for this is not yet determined, we want to give developers time to work out any issues between their code and JDK 7 first.

(Source: oracle.com.)

In Eclipse's menu Window -> Preferences -> Java -> Compiler check also "Configure Project Specific Settings".

If you stil have the error with same Java version: try to delete build folder of your project manually. Then restart Eclipse.

You have compiled your Java class with JDK 7 and you are trying to run same class on JDK 6 .

Add this to your pom.xml file:

<project ....>
    <properties>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>
</project>

Where 1.7 is the Java version you intend to use. This overwrites the Maven compiler setting, so it's good to debug from here.

Based on this...

J2SE 8 = 52
J2SE 7 = 51
J2SE 6.0 = 50
J2SE 5.0 = 49
JDK 1.4 = 48
JDK 1.3 = 47
JDK 1.2 = 46
JDK 1.1 = 45

In Eclipse, right click on project in package explorer:

Build Path -> Configure Build Path

Under:

Java Build Path -> Libraries -> Add Library -> JRE System Library -> Installed JREs -> Search.

Add the required JRE by selecting the library in the list available after the search is complete.

• Install JDK 7.0.55 and set the Java for Eclipse for JDK 7.0.55.
• Build the project with JDK 7.0.55 by configuring on build path JDK 7.0.55.
• Set the compiler in Eclipse for JDK 7.0.55 by menu Windows -> Preferences -> Java -> Compiler - choose 1.7.

I had the same problem after switching to JDK 6 to compile a dependency module, then switched but to JDK 8.
Rerun the probject and compiler complained about unsupported major.minor version. I verified the Java version it was 1,8 for both the JVM and Maven.
After many tries and googling the problem was not solved, so i though what if i restart the computer (Windows 8) ?
I did restart, rerun the project again and problem was solved :)

I solved this issue for me by checking that Maven Dependencies were being deployed in Deployment Assembly. In my case they were not.

Adding it fixed the problem.

Many answers refer to IDE's like Eclipse. However, the question relates to native development with Notepad++.

The core reason of the named error is a mismatch of the used Java Runtime Environment and used classes respectively libraries. The goal of the following descriptions is to compile without any additional installation.

1) Check the definition in the PATH variable. If there is defined:

C:\Program Files (x86)\Common Files\Oracle\Java\javapath

and/or

C:\ProgramData\Oracle\Java\javapath

These paths link to java/javac with a fixed java version. You can check this versions in this folder with javac -version. Result can be:

java version "1.8.0_231"

This means, Java version 8 is in use. Replace this entries with %JAVA_HOME%\bin. If the JDK's was installed manually, check whether JAVA_HOME is set in the environment. If not, add it, here e.g. with:

JAVA_HOME="C:\Program Files\Java\jdk1.7.0_80"

2) I have build the project on command-line with gradle. In build.gradle was defined:

android {
    buildToolsVersion "24.0.1"
    dependencies {
        compile 'com.android.support:design:23.0.1'
        compile 'com.android.support:support-v4:23.0.1'
        ...
    }
    ...
}

The used build-tools dx-files are newer then other components. Therefore a modification is required:

buildToolsVersion "23.0.1"

The answer is for the problem:

Exception in thread "main" java.lang.UnsupportedClassVersionError: edu/stevens/cs549/dhts/main/LocalContext : Unsupported major.minor version 52.0

I was having the same problem. For those who were having this trouble in AWS ec2 instances, and have somehow got redirected here to this question. I am answering for those, and would like to share that how I did it. I was having the trouble because Amazon EC2 instances were running java version 1.7 and maybe my project was not compatible with it because I was using Maven and it kind of preconfigured for java 1.8. So I installed new version of java:

sudo yum -y install java-1.8.0

And then the important step is to remove the older version:

sudo yum remove java-1.7.0-openjdk

Remember to delete it after installing the new version, else it would continuously be using the same older version and I hope it resolves your problem, which did in my case.

If someone is using Gradle, then put this in build.gradle

java { sourceCompatibility = JavaVersion.VERSION_1_7 targetCompatibility = JavaVersion.VERSION_1_7 }

We are telling the compiler to enable the byte code to be compatable with version java 7(java version in which i want to run the class) in the above case.

I have faced the same problem, and I fixed it in Linux.

Check your $JAVA_HOME

Need JDK 1.8 to compile/build APK

Install Java JDK 1.8 and change the JAVA_HOME

Edit ~/.bashrc and add your JDK 1.8 path as JAVA_HOME.

export JAVA_HOME=/usr/lib/jvm/java-8-oracle/jre/

And source ~/.bashrc

Close the current terminal window/tab and run $JAVA_HOME to check the path.

If you have a second project added to your build path make sure it has the same compiler version as your first one: Properties -> Java Compiler -> Compiler compliance level

I'm using OS X v10.11.5 (El Capitan), and I tried setting JAVA_HOME and forcing the "correct" Java version via Maven. Nothing helped.

The problem happened when the OS X account was logged out while the application was still running. After logging in again, OS X opened the old terminal session with greyed-out history. I used the same terminal session to build the project, but failed with the unsupported class version error.

Cleaning the Maven project didn't help at all.

To solve the problem, I simply had to close the auto-opened terminal window and use a new one.

The most common issue is misconfiguration of your JAVA_HOME variable which should point to the right Java Development Kit library, if you've multiple installed.

To find where SDK Java folder is located, run the following commands:

jrunscript -e 'java.lang.System.out.println(java.lang.System.getProperty("java.home"));'

Debian/Ubuntu

To check which java (openjdk) you've installed, check via:

dpkg -l "openjdk*" | grep ^i

or:

update-java-alternatives -l

To change it, use:

update-alternatives --config java

^{Prefix with sudo if required.}

to select the alternative java version.

Or check which are available for install:

apt-cache search ^openjdk

^{Prefix with sudo if required.}

Then you can install, for example:

apt-get install openjdk-7-jre

^{Prefix with sudo if required.}

Fedora, Oracle Linux, Red Hat

Install/upgrade appropriate package via:

yum install java-1.7.0-openjdk java-1.7.0-openjdk-devel

The java-1.7.0-openjdk package contains just the Java Runtime Environment. If you want to develop Java programs then install the java-1.7.0-openjdk-devel package.

BSD

There is an OpenJDK 7 package in the FreeBSD Ports collection called openjdk7 which probably needs to be reconfigured.

See: OpenJDK wiki page.

Windows

Just install appropriate Java SE Development Kit library from the Oracle site or install

Jenkins

If you're experiencing this issue with Jenkins, see:

• JENKINS-30561 - Unable to launch agent using SSH

However selecting the right version of Java (newer) with update-alternatives should work.

Had this problem when I reverted to Java 6 and tried to run classes previously compiled with Java 7. What worked for me was Preferences > java > compiler --> set compliance level to 1.6 and crucially "configure project settings"..

You are trying to run your program with a Java version that does not support the version in which the code was compiled. So basically you must have compiled your code with a higher version and trying to run it using a lower version.

As you are getting

Unsupported major.minor version 51.0

and version 51.0 corresponds to J2SE 7 you have most probably compiled your code in Java 7 and trying to run it using a lower version. Check what java -version displays. It should be the Java 7 version. If not make appropriate changes in the PATH/JAVA_HOME. Or you can compile with the same version you are trying to run the code. If the configurations are confusing you can always give absolute path /home/user/jdk1.7.0_11/bin/javac and /home/user/jdk1.7.0_11/bin/java.

Today, this error message appeared in our Tomcat 7 on Ubuntu 12.04.2 LTS (Precise Pangolin):

/var/log/tomcat7/localhost.2014-04-08.log:
Apr 8, 2014 9:00:55 AM org.apache.catalina.core.StandardContext filterStart
SEVERE: Exception starting filter struts2
java.lang.UnsupportedClassVersionError: controller/ReqAccept : Unsupported major.minor version 51.0 (unable to load class controller.ReqAccept)

The Struts application is compiled with Java 7.

It turned out, someone uses "service tomcat [stop/start]" to restart Tomcat 7,

$ ps -ef | grep java
tomcat7 31783 1 32 20:13 ? 00:00:03 /usr/lib/jvm/default-java/bin/java...
$ /usr/lib/jvm/default-java/bin/java -version
java version "1.6.0_27"

Which causes the "Unsupported major.minor version 51.0" error.

When we used "/etc/init.d/tomcat7 [stop/start]" to restart Tomcat 7, the problem was solved.

$ ps -ef | grep java
tomcat7 31886 1 80 20:24 ? 00:00:10 /usr/local/java/jdk1.7.0_15/bin/java
$ /usr/local/java/jdk1.7.0_15/bin/java -version
java version "1.7.0_15"

First let's get some basics right...

JRE is a component in NetBeans/Eclipse/standalone that is going to provide you with libraries, JVM, Java plugins & Java web start. Note that it does not provide compliers or debuggers.

JDK is the superset of JRE along with compliers and debuggers.

So when you have your default library as a JRE instead of JDK, you are going to have a nice time importing stuff, but it won't compile.

Instead, set your path to JDK (I use NetBeans, and I set them using netbeans.conf in netbeans/etc/netbeans.conf and change the path).

For me, I was getting this error on the com/sun/javadoc/Doclet class. After some digging, I found that I accidentally copied the tools.jar from Java 8 into my Java 7 folder.

Finding the tools.jar for Java 7 and putting it back into the folder fixed my issue. So something to try.

I got the same problem with a project written in 1.7 and tried to execute in 1.6.

My solution in Eclipse:

• Right click on your Project Properties -> Java Build Path -> Libraries

• Select your JRE System Library and click Edit on the right, and choose the target JRE.

• Now go to Java Compiler on the left, and change the Compiler compliance level to your target.

That worked for me.

Oh Mac OS X I was able to solve this problem by setting the JAVA_HOME variable:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_75.jdk/Contents/Home

you can specify the "target" for the compiler in the build.xml file, if you are using ant, just like below:

 <target name="compile" depends="init">
    <javac executable="${JAVA_HOME}\bin\javac" srcdir="${src.dir}" target="1.6" destdir="${classes.dir}" debug="true"
        deprecation="true" classpathref="compile.classpath" encoding="utf8">
        <include name="**/*.java" />
    </javac>
</target>

Try changing you java from java6 to java8.It might help.

Don't worry, I got it solved.

It is actually simple - you need to install BOTH JRE / JDK with the same version.

JRE 6 -> JDK 6

JRE 7 -> JDK 7

And so on.

If you're facing this issue while using Maven, you can compile your code using the plug-in Maven Compiler.

 <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
       .....

UPDATE: set source and target to 1.8, if you are using JDK 8.

In my case the problem was in the server runtime configuration:

Check the JRE is the version you need:

The project was in version 1.7 and the server JRE was set as 1.6, after changing to the proper java version it's launched fine.

You can have some JAR library compiled in Java 7, and you have only Java 6 as Java Runtime. It could happen with some new libraries.

I tried everything. Reinstalling Tomcat is what finally worked. Here's what I've checked before reinstalling.

Make sure your environmental variables look like this.

$ echo $JAVA_HOME
C:\Program Files\Java\jdk1.7.0_51\
$ echo $JRE_HOME
C:\Program Files\Java\jdk1.7.0_51\jre\bin

Make sure Eclipse is using the same jre you set JAVA_HOME to (if JAVA_HOME is not set it will look at JRE_HOME). Window > Prefrences > Java > Installed JREs (the checked one is the default one)

If you made any changes to any of your tomcat files especially catalina.bat or startup.bat, then you may be telling tomcat to look at a different version of java than the one you set to JAVA_HOME C:\Program Files (x86)\Apache\apache-tomcat-7.0.26\bin

I had the problem whereby I was having to run a Maven compilation on my project from the command line in order to run my unit tests; if I made a change to the test class and let Eclipse automatically recompile it, then I got the "Unsupported major.minor version 51.0" error.

I do have both JDK6 and JDK7 installed, but all my JRE settings were pointing at 1.6, both in the pom and from the project properties page in Eclipse. No amount of Maven Update Project and/or refreshing solved this.

Finally I tried closing the project and re-opening it, and this seemed to fix it! HTH

This error means you're trying to load a Java "class" file that was compiled with a newer version of Java than you have installed.

For example, your .class file could have been compiled for JDK 7, and you're trying to run it with JDK 6.

So the solution is to either:

• Upgrade your Java runtime or

• Recompile the class if you have the source, using your local Java compiler (if you have one).

  javac FileName.java

For developers, this can happen if another developer checks in a .class file, and they've got a newer version of java than you have!

I have faced the same problem when I was working with an Ant script to build my application.

I use Eclipse for my application development, and I changed the compiler version in build properties of the project. But that didn't work for me. Then I found out that I can provide the compiler version in the Ant script.

I modified the Ant script at the section where it compile Java files.

<target name="build-java" depends="prepare-build">
    <echo message="Compiling java files"/>
    <javac ....
           target="1.5"...
    </javac>
</target>

This worked for me to resolve the unsupported major minor issue.

I had a similar situation on Mac, and the following process worked for me:

In the terminal, type

vi ~/.profile

Then add this line in the file, and save

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk<version>.jdk/Contents/Home

where version is the one on your computer, such as 1.7.0_25.

Exit the editor, then type the following command make it become effective

source ~/.profile 

Then type java -version to check the result

java -version 

What is .profile file?

.profile file is a hidden file. It is an optional file which tells the system which commands to run when the user whose profile file it is logs in. For example, if my username is bruno and there is a .profile file in /Users/bruno/, all of its contents will be executed during the log-in procedure.

Source: http://computers.tutsplus.com/tutorials/speed-up-your-terminal-workflow-with-command-aliases-and-profile--mac-30515

Since java 9 -target is replaced by --release.

Till java 11, the available numbers for --release are 6 7, 8, 9, 10, 11.
And you can guess the future versions will be 12, 13, and go on.

To compile for an older target jvm, using javac --release 7 Tmp.java // this will generate .class file that could run on jvm >= 7,

Then you can check the target version via:

javap -v Tmp | grep version

in the output, major version identify the target jvm version.

• 55 -> java 11
• 54 -> java 10
• 53 -> java 9
• 52 -> java 8
• 51 -> java 7
• 50 -> java 6

Future version will remove more older versions:

• As of java 11, major versions <= 49 (java version <= 5), are not supported.
• As of java 12 and 13, major versions <= 50 (java version <=6), are not supported.

You can find out which target versions are support by current javac, via command:
javac -help | grep releases

As answered elsewhere by several people, the Java program is being run on an older version of Java than the one it was compiled it for. It needs to be "crosscompiled" for backward compatibility. To put it another way, there is a mismatch between source and target Java versions.

Changing options in Eclipse menus don't answer the original poster, who said he/she is not using Eclipse. On OpenJDK javac version 1.7, you can crosscompile for 1.6 if you use parameters -source and -target, plus provide the rt.jar -file of the target version (that is, the older one) at compile time. If you actually install the 1.6 JRE, you can point to its installation (for example, /usr/lib/jvm/java-6-openjdk-i386/jre/lib/rt.jar on Ubuntu, /usr/jdk/jdk1.6.0_60/jre/lib/rt.jar on SunOS apparently. Sorry, I don't know where it is on a Windows system). Like so:

javac -source 1.6 -target 1.6 -bootclasspath /usr/lib/jvm/java-6-openjdk-i386/jre/lib/rt.jar HelloWorld.java

It looks like you can just download rt.jar from the Internet, and point to it. This is not too elegant though:

javac -source 1.6 -target 1.6 -bootclasspath ./rt.jar HelloWorld.java