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Unsupported major.minor version 51.0

p_wilson
Champ in-the-making
Champ in-the-making
Good evening all,
this is my first post but I have been in and out of these forums for weeks. It's been very helpful and now I have a little problem that I can't seem to find the answer to.

Yesterday I had a fully running activiti setup, running both rest and explorer instances.
Unfortunately, I had to do a rebuild of the server and since then I am having problems getting my processes to instantiate my custom jars.

Previously I was using Activiti 5.13, the new install is with 5.14.The corresponding eclipse included jars have been updated to represent this change in version. In fact I started a completely new project just in case it was using files from the previous install.

When I run my process, that uses a service task to call a class, I get an error saying "couldn't instantiate class".
The relevant export jar files are located in their respective  **/WEB-INF/lib directories.

On closer inspection of the error stack trace I noticed the line:-
 
Caused by: java.lang.UnsupportedClassVersionError: Dbk_mysqlConnector : Unsupported major.minor version 51.0 (unable to load class    Dbk_mysqlConnector)


I am not able to find any previous reported errors with this problem.
The setup is on Debian, Tomcat 7, Java 7, Activiti 5.14 and I have included the full stacktrace in the attached file.

Any help would be appreciated.
Regards
Phil.

3 REPLIES 3

martin_grofcik
Confirmed Champ
Confirmed Champ
It is not an activiti error. Which version of JRE are you using?
(class is compiled with java 7)

Oh, I am using Oracle java 7.
Now that I know it is a java issue I will give it a tinker today and see what I can see.

p_wilson
Champ in-the-making
Champ in-the-making
This issue is now solved.

The problem was an improper java installation on the debian server.

To solve an error such as this it was necessary to remove all and any previous versions of java that may exist (for me this was openjdk which was installed automatically by my 'kind' VPS providers when they did a clean rebuild of the operating system). It is then a simple matter of re-installing oracle java 7 and ensuring the paths are correctly set.

Activiti 5.14 is now up and active.

I hope that this will be helpful to someone.

Regards
Phil