Query: UnsupportedClassVersionError: has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version (..)up to 52.0
Context: The real problem was, you built classes before by some upgraded version of JDK than what you currently have. I too faced a similar issue, which I solved in Eclipse by following steps: Project Properties (Alt + EnterKey) -> Java Build Path -> "Libraries" section -