Every Java class file contains a version number that specifies the version of the class file format. This error is thrown when the Java Virtual Machine attempts to read a class file with a version number it does not support.

Figure 10-70. java.lang.UnsupportedClassVersionError

public class UnsupportedClassVersionError extends ClassFormatError {
// Public Constructors
     public UnsupportedClassVersionError( );  
     public UnsupportedClassVersionError(String s);  
}