Hello everyone,
I am currently upgrading an old Java project and running into a runtime configuration issue. When I compiled my source code using a newer JDK version and tried to execute the compiled .class file on a server running an older JRE, I received the following error message:
"java.lang.UnsupportedClassVersionError: Unsupported major.minor version 61.0"
I understand this happens due to a mismatch between the compiler version and the runtime environment version.
Could anyone please guide me on the best way to resolve this? Should I downgrade my JDK compilation target or upgrade the server environment? If downgrading is preferred, what are the specific compiler flags or IDE settings I should modify?
Any detailed explanation or step-by-step solution would be highly appreciated. Thank you!
fabulousfoamparty
(180 Points)
vishalrana
(3.7K Points)
I want to share clear details about this Java error. You will understand easily. The error occurs because the application was compiled with a new Java version than the existing Java version at runtime (Newer Java Version ). The main issue is the Java coding structure. The 'Unsupported major. minor version 61.0' message indicates that the class was compiled for Java 17 (class file version 61), but the server is running the old Java Runtime Environment, which cannot understand that bytecode.
1. Upgrade the server's JAVA JRE/JDK to Java 17 or later so that it matches the version used during compilation.
2. If it is not possible to upgrade the server, compile for an older Java version. For example, if the server runs on Java 11, compile like this:
javac --release 11 MyClass.java
Or try it
javac -source 11 -target 11 MyClass.java
Are you using Maven to configure the compiler?
<properties>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
</properties>
If you want to check the Java version, use command
java -version
javac -version
In my opinion and standard way, upgrading the runtime environment is the preferred solution if possible, since it allows you to use newer Java features and security updates. Otherwise, recompile the application targeting the Java version installed on the server.
In this way, you can fix your error "java.lang.UnsupportedClassVersionError: Unsupported major.minor version 61.0"
