The unsupported major.minor version error in Java arises when a class is compiled with a higher version of the Java Development Kit (JDK) but executed with a lower version of the Java Runtime Environment (JRE), resulting in a version mismatch. Java's backward compatibility allows binaries compiled on a lower version to run on higher versions, but not vice versa, as features in newer JDK versions may not be supported by older JREs. For example, a class compiled with JDK 1.8 (major version 52) cannot run on JRE 1.7, leading to the unsupported major.minor version 52.0 error. Solutions include aligning JDK and JRE versions by upgrading the JRE or downgrading the JDK, or using the Java compiler's cross-compilation option with the javac -target command to generate compatible .class files. Additionally, tools like Rollbar can aid in tracking and managing Java errors in real-time, thus easing the deployment of production code.