javac "--release" Flag Mismatch With source/target - Fix in CI

javac rejected the combination of --release with --source/--target. The two cross-compilation schemes are mutually exclusive; the build configured both.

What this error means

Compilation fails immediately with option --release cannot be used together with --source or --target. The error is about flag combination, not your code.

javac

error: option --release cannot be used together with --source or --target
Usage: javac <options> <source files>

Common causes

Both release and source/target configured

Setting maven.compiler.release while also setting maven.compiler.source/target (or release plus sourceCompatibility/targetCompatibility in Gradle) passes both flag families to javac, which is illegal.

Inherited config collides with a new release setting

A parent POM or convention plugin sets source/target while the module adds release, producing the conflict at compile time.

How to fix it

Use release only (Maven)

Prefer maven.compiler.release; remove source/target so only one scheme is passed.

pom.xml

<properties>
  <maven.compiler.release>17</maven.compiler.release>
  <!-- remove maven.compiler.source and maven.compiler.target -->
</properties>

Use one scheme (Gradle)

Set the release via the compiler options and drop sourceCompatibility/targetCompatibility, or vice versa.

build.gradle.kts

tasks.withType<JavaCompile> {
    options.release.set(17)
}
// do not also set sourceCompatibility / targetCompatibility

How to prevent it

Standardize on --release everywhere and remove source/target, checking parent POMs and convention plugins for inherited settings.