can't upgrade jenkins for java version error
You're using Java 7, but Jenkins needs Java 8 - see: https://jenkins.io/blog/2017/04/10/jenkins-has-upgraded-to-java-8
You need JDK 8 to run jenkins:https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-get-on-ubuntu-16-04
Update your java version by using these commands,
sudo -E add-apt-repository ppa:openjdk-r/ppa sudo apt-get updatesudo apt-get install openjdk-8-jdkand follow this command to change your default selection mode of java version.
sudo update-alternatives --config javaIt should be set to java 8 values.