class file has wrong version 49.0, should be 48.0

If you get below mentioned error.

class file has wrong version 49.0, should be 48.0

There could be Java version conflict. Check for correct version of Java for Compiling and Running the .class / .jar file.
You may have complied .java file in higher version of Java and Running it on lower version of Java.

Check for Java version

Command: java -version

Just make sure that you compile and run in same version.