When you try to launch a Java jar application from the Terminal/Command Line and you get "A Java Exception has occurred", the most likely reason is that a Runtime exception or an Error has occurred when trying to execute the program.
How to fix Exception Occurred Issue
- Go to the console and see what exception stack trace you see and try to collect more information.
The most common reason is that you are using a different version while running the Java application and you get an UnsupportedClassVersionError.
Exception in thread "main" java.lang.UnsupportedClassVersionError: Unsupported major minor version 63.0 ...
Another most common exception you will see is NoClassDefFoundError
Exception in thread "main" java.lang.NoClassDefFoundError:
- Make sure that the Java version during executing the program is compatible with the application.
- It could be so that you are using 3rd party dependencies that are either not available during running the application or are properly configured.
- If you see a OutOfMemoryError: PermGen Exception you would need to increase the JVM memory allocation using the -Xmx parameter.
- Go back to your IDE and try to run the application in debug mode to identify what has caused the exception.
![Java Virtual Machine Launcher - A Java Exception has occurred Java Virtual Machine Launcher - A Java Exception has occurred](https://code2care.org/q/fix-a-java-exception-has-occured-java-virtual-machine-launcher/images/Java Virtual Machine Launcher - A Java Exception has occured.jpg)
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Rakesh (He/Him) has over 14+ years of experience in Web and Application development. He is the author of insightful How-To articles for Code2care.
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