root@jenkins:/# cat /etc/apt/sources.list

deb http://ftp.debian.org/debian wheezy main contrib non-free

deb http://security.debian.org wheezy/updates main contrib non-free

 

 

root@jenkins:/# tac /path/to/jenkins.log | less

(...)

java.lang.UnsupportedClassVersionError: 50.0

Jenkins requires Java7 or later, but you are running 1.6.0_35-b35 from /usr/lib/jvm/java-6-openjdk-amd64/jre

        at Main.main(Main.java:90)

java.lang.UnsupportedClassVersionError: 50.0

Jenkins requires Java7 or later, but you are running 1.6.0_35-b35 from /usr/lib/jvm/java-6-openjdk-amd64/jre

(...)