What Is This Error?

When running code in IntelliJ IDEA, you may see this message:

Error:java: javacTask: source release 8 requires target release 1.8

It indicates a mismatch between the source level and the target bytecode level. The fix is straightforward.

Fix

Update IntelliJ settings. On macOS, follow this path and set the module target bytecode.

intellij settings

Maven Fix

If you use Maven, add compiler settings in pom.xml instead of changing IDE settings.

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>

Closing Notes

IntelliJ lets you set Project SDK and Language Level at the project level. You can also set them per module.

intellij project settings

Project SDK (left) and per-module SDK/Language Level (right)

Even if the compiler level is set to Java 8, compilation still fails when the Language Level is lower than the target bytecode level.

not supported source version

java: try-with-resources is not supported in -source 1.5 (use -source 7 or higher to enable try-with-resources)