When I try to install the new version 2.55, I get the same 503 "Service Unavailable" error that I received when trying to install version 2.54. I have to revert back to 2.53 to get Jenkins to work. The server where Jenkins is installed has Java 8 on it.
java version "1.8.0_74"
Java(TM) SE Runtime Environment (build 1.8.0_74-b02)
Java HotSpot(TM) 64-Bit Server VM (build 25.74-b02, mixed mode)
Jenkins was installed by somebody else who is no longer with our company, so I "inherited" the setup. It was installed as a service that gets automatically started every time that server is rebooted. From the jenkins.err.log file, I see:
Caused by: java.lang.UnsupportedClassVersionError: jenkins/util/SystemProperties : Unsupported major.minor version 52.0
Am I missing something here? What is going wrong? I thought version 2.55 was created to solve the problem of Jenkins using its own internal version of Java 7 instead of the server's Java 8 version.