# Java.lang.UnsupportedClassVersionError: org/elasticsearch/ElasticsearchException : Unsupported major.minor version 51.0
**URL:** https://discuss.elastic.co/t/java-lang-unsupportedclassversionerror-org-elasticsearch-elasticsearchexception-unsupported-major-minor-version-51-0/22938
**Category:** Elasticsearch
**Created:** [March 27, 2015, 6:56am UTC](https://discuss.elastic.co/t/java-lang-unsupportedclassversionerror-org-elasticsearch-elasticsearchexception-unsupported-major-minor-version-51-0/22938 "2015-03-27T06:56:23Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Vijayakumari\_B\_N](https://discuss.elastic.co/u/Vijayakumari_B_N)
#### Post date: [March 27, 2015, 6:56am UTC](https://discuss.elastic.co/t/java-lang-unsupportedclassversionerror-org-elasticsearch-elasticsearchexception-unsupported-major-minor-version-51-0/22938/1 "2015-03-27T06:56:23Z")
Hi,
I have jdk1.7.0\_75 in linux and elasticsearch server 1.4.1, but while
starting my jboss server i am getting below exception. I am able to run
elasticsearch server using same version. Any body knows what is java
compatible version for elastic search 1.4.1.
java.lang.UnsupportedClassVersionError:
org/elasticsearch/ElasticsearchException : Unsupported major.minor version
51.0
I do not have version 51 anywhere in my system, please advice
Thanks,
Vijaya
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### Author:  [@dadoonet](https://discuss.elastic.co/u/dadoonet)
#### Post date: [March 27, 2015, 8:12am UTC](https://discuss.elastic.co/t/java-lang-unsupportedclassversionerror-org-elasticsearch-elasticsearchexception-unsupported-major-minor-version-51-0/22938/2 "2015-03-27T08:12:51Z")
Even though you have installed java7, it sounds like your JAVA\_HOME is set to java6...
Check your config.
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David 😉
Twitter : @dadoonet / @elasticsearchfr / @scrutmydocs
> Le 27 mars 2015 à 07:56, Vijayakumari B N [vijayakumari.bn@gmail.com](mailto:vijayakumari.bn@gmail.com) a écrit :
>
> Hi,
>
> I have jdk1.7.0\_75 in linux and elasticsearch server 1.4.1, but while starting my jboss server i am getting below exception. I am able to run elasticsearch server using same version. Any body knows what is java compatible version for Elasticsearch 1.4.1.
>
> java.lang.UnsupportedClassVersionError: org/elasticsearch/ElasticsearchException : Unsupported major.minor version 51.0
>
> I do not have version 51 anywhere in my system, please advice
>
> ## Thanks, Vijaya
>
> You received this message because you are subscribed to the Google Groups "elasticsearch" group.
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### Author:  [@costin](https://discuss.elastic.co/u/costin)
#### Post date: [March 27, 2015, 8:20am UTC](https://discuss.elastic.co/t/java-lang-unsupportedclassversionerror-org-elasticsearch-elasticsearchexception-unsupported-major-minor-version-51-0/22938/3 "2015-03-27T08:20:52Z")
Double check you are using JDK 1.7 or higher for your Elastic/JBoss combination.
It looks like you are using JDK 1.6 - the exception indicates that the Java runtime doesn't recognize the bytecode
version (51.0 stands for Java 7 class files [1]).
The class files major versions are:
Java 8 = 52, Java 7 = 51, Java 6 = 50, Java 5 = 49
[1] [Java class file - Wikipedia](http://en.wikipedia.org/wiki/Java_class_file)
On 3/27/15 8:56 AM, Vijayakumari B N wrote:
> Hi,
>
> I have jdk1.7.0\_75 in linux and elasticsearch server 1.4.1, but while starting my jboss server i am getting below
> exception. I am able to run elasticsearch server using same version. Any body knows what is java compatible version for
> Elasticsearch 1.4.1.
>
> java.lang.UnsupportedClassVersionError: org/elasticsearch/ElasticsearchException : Unsupported major.minor version 51.0
>
> I do not have version 51 anywhere in my system, please advice
>
> Thanks,
> Vijaya
>
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 12:23am UTC](https://discuss.elastic.co/t/java-lang-unsupportedclassversionerror-org-elasticsearch-elasticsearchexception-unsupported-major-minor-version-51-0/22938/4 "2017-07-06T00:23:31Z")