java.lang.UnsupportedClassVersionError: Bad version number in .class file @Digizol

java.lang.UnsupportedClassVersionError: Bad version number in .class file
[at java.lang.ClassLoader.defineClass1(Native Method)]
is an error that you may face in running a compiled java class file.

So as you can see from the stack trace, a class has not been loaded. But which class? The problem is this error message does not show the name of the failed .class, isn't it?

No, it is not. This error is caused when you compile a .java file with one version of JDK and running the .class file with a different version of JVM.

Confused? You may say; same version is not required to compile and run.

Yes, that is true. But you can not run .class files that are compiled with a newer version than the JVM.

Say;

javac (compile) - version: X
java  (run)     - version: Y

If X is newer than Y; then you may face this issue at runtime.

Now you know how to solve this issue, isn't it?

Labels: Java, Tech

49 Comments for "java.lang.UnsupportedClassVersionError: Bad version number in .class file"

Anonymous on September 11, 2008 4:53 PM

I tried 2 run some class files on java 1.5 I received from a friend and faced this error. Thanks for pointing the solution.
Eswara Moorthi Thanaraj on November 02, 2008 10:09 AM

It's crystal clear explanation. bunch of thanks Kamal.
Anonymous on December 10, 2008 12:04 AM

Thanks Kamal! Your post helped me.
Anonymous on December 15, 2008 1:07 PM

Dear Friend im facing the same problem but as u explaned i dont know how to use these commands plz help
Kamal Mettananda on December 15, 2008 2:57 PM

Hello friend,

Please check the versions of javac and java on your computer and post them here, then we'll create the required commands.
glomdigg on January 17, 2009 9:03 PM

Wow cool
I can fix my problem by you posted
Anonymous on January 21, 2009 7:39 PM

how is it that i remember being able to issue a "javac -version" before that worked, but now i can't figure out how to check my compiler version?

java -version (always works)
javac -version (now never works)

darksalmon
prasad on February 18, 2009 1:26 AM

java version "1.6.0_12"
Java(TM) SE Runtime Environment (build 1.6.0_12-b04)
Java HotSpot(TM) Client VM (build 11.2-b01, mixed mode, sharing)

javac 1.6.0_12

I got the versions as above, but still getting this error. I have tried compiling it with or without -cp option, but it is still failing to run. I am able to get this to work from another workstation. Can you please help?
satyam on February 20, 2009 12:35 AM

im facing the same problem but when i installed 1.5 it didnt showed any error but at run time it is showing the error
and java -version is showing 1.3.1 version
satyam on February 20, 2009 9:34 AM

i installed latest 1.6 jvm and jre. javac -version is showing 1.6 but java -version is still showing 1.3 may be older version is not unistalled properly. help me
Kamal Mettananda on February 20, 2009 9:42 AM

Hi Satyam,

Best thing to resolve this would be, first remove all jre/jdk installations. (Better not to install two different versions on one machine.)

Then check for versions of both. That way you will be able to resolve this issue.
Anonymous on April 06, 2009 10:17 AM

I am getting this error for groovy 1.6.0.

java.lang.UnsupportedClassVersionError: org/codehaus/groovy/tools/GroovyStarter (Unsupported major.minor version 49.0)

and my java -version is java version "1.6.0_11"

Any thoughts?
Anonymous on April 17, 2009 6:11 PM

I think 49.0 => Java 1.5 ... are you sure all were recompiled?
Doesn't it identify the bad class file?
asad on April 21, 2009 2:10 PM

I got the same exception and I solved it
java.lang.UnsupportedClassVersionError: Bad version number in .class file
[at java.lang.ClassLoader.defineClass1(Native Method)]

I was using JDK 1.5
I was trying to connect from eclipse using "postgresql-8.3-603.jdbc4.jar"
this driver. This jdbc driver.

After the error message i went to http://jdbc.postgresql.org/download.html
and found a compatibility list like this
* JDK 1.1 - JDBC 1. Note that with the 8.0 release JDBC 1 support has been removed, so look to update your JDK when you update your server.
* JDK 1.2, 1.3 - JDBC 2.
* JDK 1.3 + J2EE - JDBC 2 EE. This contains additional support for javax.sql classes.
* JDK 1.4, 1.5 - JDBC 3. This contains support for SSL and javax.sql, but does not require J2EE as it has been added to the J2SE release.
* JDK 1.6 - JDBC4. Support for JDBC4 methods is limited. The driver builds, but the majority of new methods are stubbed out.

So i used "postgresql-8.3-604.jdbc3.jar" instead of jdbc4.

And then my connection was found by eclipse ran without any problem
gabe on August 28, 2009 9:09 PM

Thanks!
Anonymous on September 30, 2009 8:54 PM

thanks for the tips.
Anonymous on October 02, 2009 4:13 PM

I have the same problem. But i have java version 1.5.0_21 and jvm is the same but in eclipse when i start tomcat this error happens.

Any idea?

I have check everything related to java so all is pointing to this version

Thanks in advance
Kamal Mettananda on October 03, 2009 11:16 AM

// Tomcat and java version 1.5.0_21

Can you try starting Tomcat without the projects that you have deployed there? Then you will be able to locate the web application that causes this error.
Anonymous on October 14, 2009 4:36 PM

Loud and clear..Thank you
Anonymous on October 15, 2009 8:00 PM

Thankyou yaar!
Anonymous on November 03, 2009 5:04 AM

If you get this in ECLIPSE. Look at the javac compliance under Windows->Preferences->Java->Compiler and make sure its the same as Eclipse's default JRE version.

This was driving me nuts - until I saw my Eclipse JRE was 1.5 and this setting was at 1.6!!!!
Anonymous on November 20, 2009 4:16 PM

thank you for the post I find it usefull.
I find that a few days before I had installed Zend Studio on Windows 7, while replacing my JRE becoz Zend studio does't work well on this window and currently this is the one way to get it work well on Win7.
Sharad on February 02, 2010 3:49 PM

Good Solution
Anonymous on February 10, 2010 12:04 PM

Thank U very much dude.. Ur explantion was very clear..
Duval on February 13, 2010 4:35 AM

The problem is that versions of compilation (javac) and run (java) must be the same, but not necessarily in your PC. The JDBC connection is to be compatible with our PC.
So the solution is to find the appropriate JDBC.
Anonymous on March 09, 2010 4:53 AM

Of course the error message should tell me the class. In my case I have both Java 1.5 set in the Eclipse project, and the settings show that 1.5 class files are being built. I also am running with JDK1.5. Without telling me the class in error, there is no way I can trouble shoot.
Sofia Bertolini on March 26, 2010 8:48 AM

Hi all!!!

Is it possible to have version X and version Y such that Y=X and still get this?:

Error compiling the report java source!
java.lang.UnsupportedClassVersionError: Bad version number in .class file at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:676)
... and so on....

Trying to compile a jasper report on iReport 3.7.1 (netbeans platform)...

Any guess?

Grazie mille!!

Sofia
Mac OSX v. 10.5.8 Intel
Java(TM) SE Runtime Environment (build 1.6.0_17-b04-248-9M3125)
sofiad:~ sofi$ javac -version
javac 1.6.0_17
Kamal Mettananda on March 27, 2010 9:19 PM

// 27

Hi Sofia,

This error message is only there when this version conflict occurs.

Even though you are using 1.6.0_17 jdk & jre; you may be using some other jar files that were generated with classes generated with a newer version of Java. So you can check Java versions used for them as well?
Anonymous on April 21, 2010 2:45 PM

Thanks
chamira on April 28, 2010 6:33 PM

Hello,

Running from the command line (Windows XP) I have,
Java as: java version "1.4.2_03"
Javac as: javac 1.6.0_11

This is causing a conflict. I can't find the older version of the JRE in the Windows Control Panel to remove it I can only see Java 6 Update 11 and the JDK SE Update 11. I can't find any reference to the older java on the Java console in the Windows Control Panel either.

When I'm using NetBeans, everything is working correctly as it is pointing to right folders.

My PATH is C:\Program Files\Java\jdk1.6.0_11\bin

How do I remove the older version?
Chetan on May 05, 2010 5:12 PM

Well this error is due to the compiler version and JRE version are different.

If you are interested, You can easily reproduce it in Eclipse

Install jdk1.5 and Jdk1.6 in your system.

Create a simple java project in eclipse

Set the compiler version to 1.6 through menu->Windows-Preference->Compiler to 1.6

the select the project and change the buildpath jre to 1.5. (check eclipse help)

Try to run the program.

You get the this error!!!
Anonymous on May 06, 2010 1:20 AM

Thanks for the solution.
Anonymous on August 23, 2010 2:34 PM

Thanks for solving my problem.
Anonymous on September 29, 2010 3:10 PM

Thanks... my eclipse was using a different version. Problem solved.
Anonymous on October 08, 2010 12:29 AM

Thanks Kamal this post helped me...
I was running an ANT build with javac version 1.6_0 update 21
....
...
< javac srcdir="src/main/test" destdir="target/classes" classpathref="compile.classpath" />
....

The classes were getting deployed to Apache Tomcat 6.0.26 container...I think Apache Tomcat still requires version 1.5...when I added my ant script above following two conditions it redeployed ...it worked for me. Here is the updated antscript line:
< javac srcdir="src/main/test" destdir="target/classes" classpathref="compile.classpath" source="1.5" target="1.5" />
Anonymous on October 15, 2010 4:09 PM

a big thank you
Anonymous on October 21, 2010 9:11 PM

i have same problem i have jdk1.5 with mac osx and jvm 1.6 in eclipse n i cant found the sollll of this problem plz anybody suggest me but i have to do.........
javier on December 02, 2010 4:39 AM

Wow, thank you, very nice and clear explanation. Refering to Eclipse (in my case) specifically, you have to go preferences->java->installed JREs an then check which you prefer.
shankar on January 19, 2011 5:43 PM

this problem will be arised bcoz of jdk and jre are not the same version.
Brad Fallon on February 11, 2011 10:07 PM

how to do 4x4 tiles with red n blue color using method start() it can changed into other color in JAVA lang?
fico score on February 23, 2011 11:03 PM

I have deleted/reloaded Java 25 times. Get the same error: java.lang.ClassFormatError:Truncated class file???
kumaran on April 15, 2011 7:43 PM

Crisp and clear mate , i hav resolved the problem in short time thanks for the post.
Anonymous on June 17, 2011 7:29 AM

Thanks for article...solved the problem
Anonymous on July 08, 2011 12:47 AM

Hi,

I have a question that if I compile and build (war and ear files) with 1.6.0_22 and my weblogic server is running on 1.6.0_11, then will it work?

Both are using java 1.6 but server has 1.6 with updates 11 and in my system I have Java 1.6 with update 22.

Please put your suggestions.

Thanks in advance !!!!

-RP
Anonymous on September 07, 2011 9:30 PM

Thanks very much...That was the best explanation i got on net.
3 Cheers!....
:D
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Combining class files into a JAR file to make standalone program?
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I am having prolems loading some pages due to a java error. How can I fix the problem?
icon brickell on January 09, 2012 9:23 PM

I am having prolems loading some pages due to a java error. How can I fix the problem?