Unsupported Class File Major Version 66

When compiling Java code, you may encounter the error message "Unsupported class file major version 66." This error indicates that the Java compiler is unable to recognize the version of the class file you are trying to compile. The class file major version is a number that indicates the version of the Java Virtual Machine (JVM) that was used to create the class file. The current version of the JVM is 17, and the corresponding class file major version is 60.

The error message "Unsupported class file major version 66" can occur if you are trying to compile code that was created using a newer version of the JVM than the one you are currently using. For example, if you are using Java 11 to compile code that was created using Java 17, you will encounter this error.

To resolve this error, you need to update the version of the JVM that you are using to a version that supports the class file major version of the code you are trying to compile. You can download the latest version of the JVM from the Oracle website.

Once you have updated the version of the JVM, you should be able to compile the code without encountering the "Unsupported class file major version 66" error.

Troubleshooting Tips

If you are still encountering the "Unsupported class file major version 66" error after updating the version of the JVM, you can try the following troubleshooting tips:

• Make sure that you are using the correct version of the Java compiler. The Java compiler is included with the JDK, so you need to make sure that you are using the same version of the JDK as the version of the JVM.
• Check the classpath to make sure that it includes the correct version of the Java library. The Java library is a set of classes that are used by the Java compiler and the JVM. If the classpath does not include the correct version of the Java library, the compiler may not be able to find the classes it needs to compile the code.
• Try recompiling the code using a different Java compiler. There are a number of different Java compilers available, so you may be able to resolve the error by using a different compiler.

Conclusion

The "Unsupported class file major version 66" error can be a frustrating problem, but it is usually easy to resolve. By following the troubleshooting tips in this article, you should be able to get your code compiling without errors.

Additional Information

• Oracle Java website
• Java compiler documentation
• Java class file format

FAQs

• What is the class file major version?

The class file major version is a number that indicates the version of the JVM that was used to create the class file.

• Why do I get the "Unsupported class file major version 66" error?

You get this error if you are trying to compile code that was created using a newer version of the JVM than the one you are currently using.

• How do I resolve the "Unsupported class file major version 66" error?

You can resolve this error by updating the version of the JVM that you are using to a version that supports the class file major version of the code you are trying to compile.

• What are some troubleshooting tips for the "Unsupported class file major version 66" error?

If you are still encountering the error after updating the version of the JVM, you can try the following troubleshooting tips:

* Make sure that you are using the correct version of the Java compiler.
* Check the classpath to make sure that it includes the correct version of the Java library.
* Try recompiling the code using a different Java compiler.