HTTP Status 500: Error Unsupported Major.minor version 51.0 (unable to load class XXX)

This is caused by the JDK version and the JRE mismatch.

Error message:

Detailed questions:(to be filled out)

Processing:

1. Check if JDK and JRE versions match

--Open command line interface (CMD), enter java-version and javac-version respectively to view version information

If it does not match, download the corresponding JRE or JDK version yourself

If it's a match like mine, then go on:

2. Since it is a match, it is the JDK version of the problem. You can choose to adjust the JDK version (originally 1.7), and finally Apply-->ok

Restart the server again, the problem is solved.

HTTP Status 500: Error Unsupported Major.minor version 51.0 (unable to load class XXX)