quarkusio/quarkus · error · GradleException

Failed to clean up non-modified jars in lib/

Error message

Failed to clean up non-modified jars in lib/

What it means

During assembleLegacyJar, the Quarkus Gradle plugin deletes stale, non-modified jars from the lib/ directory of a previous legacy-jar build. If any file-system traversal or delete fails with IOException, the whole assemble step aborts with a GradleException. The original cause is not chained in this case, so the message alone must be investigated.

Source

Thrown at devtools/gradle/gradle-application-plugin/src/main/java/io/quarkus/gradle/tasks/QuarkusBuild.java:277

            copy.include("lib/**");
        }));

        // Quarkus' 'legacy-jar' package type produces 'lib/modified-*.jar' files for some dependencies.
        // The following code block removes the non-modified jars.
        getLogger().info("Cleaning up lib/ directory in {}", buildDir);
        try (Stream<Path> files = Files.walk(libDir)) {
            files.filter(Files::isRegularFile).filter(f -> f.getFileName().toString().startsWith("modified-"))
                    .map(f -> f.getParent().resolve(f.getFileName().toString().substring("modified-".length())))
                    .toList() // necessary :(
                    .forEach(f -> {
                        try {
                            Files.deleteIfExists(f);
                        } catch (IOException e) {
                            throw new RuntimeException(e);
                        }
                    });
        } catch (IOException e) {
            throw new GradleException("Failed to clean up non-modified jars in lib/");
        }

        copyRunnersAndArtifactProperties(appBuildDir);
    }

    private void assembleFullBuild() {
        File targetDir = buildDir;

        // build/quarkus-build/gen
        Path genBuildDir = genBuildDir();

        if (nativeEnabled()) {
            if (nativeSourcesOnly()) {
                getLogger().info("Copying Quarkus build for native sources from {} into {}", genBuildDir, targetDir);
            } else {
                getLogger().info("Copying Quarkus native build from {} into {}", genBuildDir, targetDir);

            }

View on GitHub (pinned to e1c734241f)

Solutions

1. Stop any running Quarkus dev-mode or java -jar process that locks jars in build/ (or the app build dir) and rebuild
2. Check permissions on the build output lib/ directory and delete it manually: rm -rf build/quarkus-app (or the configured build directory)
3. On Windows, close file explorers/antivirus scanning the lib dir, or restart to release locks
4. Run ./gradlew clean then re-run the build

Example fix

// shell-side fix
./gradlew stop # if using quarkusDev in another terminal
rm -rf build/quarkus-app
./gradlew quarkusBuild

// before quarkusBuild, ensure nothing holds build/ open and the dir is writable
assert new File("build/quarkus-app").canWrite() || !new File("build/quarkus-app").exists();

try {
    ./gradlew quarkusBuild
} catch (GradleException e) {
    if (e.message?.startsWith("Failed to clean up non-modified jars")) {
        "./gradlew clean".execute().waitFor(); retryBuild();
    } else { throw e; }
}

When it happens

Trigger: IOException while walking/deleting files under the app build directory's lib/ (e.g. file locked by a running application, permission denied, directory deleted concurrently) in QuarkusBuild.assembleLegacyJar, called from finalizeQuarkusBuild.

Common situations: A previously started quarkusDev/quarkusRun JVM or an IDE still holds jar handles (Windows especially); build directory owned by another user after running with sudo; read-only CI workspace.

Related errors

• Failed to resolve ${appArtifact}
• Requested artifact ${appArtifact} does not match project ${g
• No platforms detected in the project
• Failed to determine the Quarkus core version for the project
• Failed to configure ${taskPath}: sourceSet ${sourceSet} has

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/34de57a3a77f78ae. Report an issue: GitHub.