I I have upgraded the jenkins version from 1.4 to 1.649 ,after migration My Java 1,5 projects are not compiling ending with following exception,but 1,6 and 1,7 projects are compiling.

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Parsing POMs
[maven-versioninfo-plugin] $ /srv/hudson/tools/Java-1.5.x/bin/java -Xmx512m -Xms64m -XX:PermSize=64m -XX:MaxPermSize=128m -cp /srv/hudson/maven-agent.jar:/srv/hudson/classworlds.jar hudson.maven.agent.Main /srv/hudson/tools/maven-2.0.x /srv/hudson/slave.jar /srv/hudson/maven-interceptor.jar 44373
<===[HUDSON REMOTING CAPACITY]===>���channel started
channel stopped
ERROR: POMs konnten nicht geparst werden
java.io.IOException: Remote call on Channel to Maven [/srv/hudson/tools/Java-1.5.x/bin/java, -Xmx512m, -Xms64m, -XX:PermSize=64m, -XX:MaxPermSize=128m, -cp, /srv/hudson/maven-agent.jar:/srv/hudson/classworlds.jar, hudson.maven.agent.Main, /srv/hudson/tools/maven-2.0.x, /srv/hudson/slave.jar, /srv/hudson/maven-interceptor.jar, 44373] failed
at hudson.remoting.Channel.call(Channel.java:638)
at hudson.maven.ProcessCache$MavenProcess.call(ProcessCache.java:156)
at hudson.maven.MavenModuleSetBuild$RunnerImpl.doRun(MavenModuleSetBuild.java:665)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:420)
at hudson.model.Run.run(Run.java:1362)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:424)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:145)
Caused by: java.lang.UnsupportedClassVersionError: Bad version number in .class file
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.lang.ClassLoader.defineClass(ClassLoader.java:465)
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:151)
at hudson.remoting.RemoteClassLoader.findClass(RemoteClassLoader.java:131)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)