elastic/elasticsearch · error · GradleException

Unsupported classpath element: {}

Error message

Unsupported classpath element: {}

What it means

Thrown by SplitPackagesAuditTask.readPackages when a classpath element passed to the audit is neither a filesystem directory nor a file ending in .jar. The method only handles directories and jars; any other artifact type (e.g. a .zip, .class, or symbolic link to neither) falls into the else branch and aborts.

Source

Thrown at build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/precommit/SplitPackagesAuditTask.java:313

            }
        }

        // TODO: want to read packages the same for src dirs and jars, but src dirs we also want the files in the src package dir
        private static Set<String> readPackages(File classpathElement) {
            Set<String> packages = new HashSet<>();
            Consumer<Path> addClassPackage = p -> packages.add(getPackageName(p));

            try {
                if (classpathElement.isDirectory()) {
                    walkJavaFiles(classpathElement.toPath(), ".class", addClassPackage);
                } else if (classpathElement.getName().endsWith(".jar")) {
                    try (FileSystem jar = FileSystems.newFileSystem(classpathElement.toPath(), Map.of())) {
                        for (Path root : jar.getRootDirectories()) {
                            walkJavaFiles(root, ".class", addClassPackage);
                        }
                    }
                } else {
                    throw new GradleException("Unsupported classpath element: " + classpathElement);
                }
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }

            return packages;
        }

        private static void walkJavaFiles(Path root, String suffix, Consumer<Path> classConsumer) throws IOException {
            if (Files.exists(root) == false) {
                return;
            }
            try (var paths = Files.walk(root)) {
                paths.filter(p -> p.toString().endsWith(suffix))
                    .map(root::relativize)
                    .filter(p -> p.getNameCount() > 1) // module-info or other things without a package can be skipped
                    .filter(p -> p.toString().startsWith("META-INF") == false)
                    .forEach(classConsumer);

View on GitHub (pinned to db6a809a66)

Solutions

1. Inspect the Gradle dependency graph for the failing project (./gradlew :<project>:dependencies) and find which dependency resolves to a non-jar, non-directory artifact.
2. Exclude or correct the offending dependency/configuration so the audit only sees directories and .jar files.
3. If a legitimate non-jar archive must be audited, extend readPackages to handle that extension, but first verify the artifact is genuinely required on the classpath.
4. Clear the Gradle cache for the suspect artifact (rm -rf ~/.gradle/caches/modules-2/...) and re-resolve to rule out cache corruption.

// Validate classpath elements before passing them to the audit
for (File f : classpathElements) {
    if (f.isDirectory() == false && f.getName().endsWith(".jar") == false) {
        throw new IllegalArgumentException("Unsupported classpath element for audit: " + f);
    }
}

try { Set<String> pkgs = SplitPackagesAuditTask.readPackages(element); }
catch (GradleException e) {
    if (e.getMessage().startsWith("Unsupported classpath element")) { /* log + skip or fix config */ }
    else throw e;
}

When it happens

Trigger: The audit receives a File classpathElement that is not a directory and whose name does not end with .jar — for example a raw .class file, a .zip archive, or an unresolved/pom artifact. This typically happens when a project dependency resolves to an unexpected artifact type or when a custom configuration feeds non-jar entries into the audit.

Common situations: Adding a dependency that resolves to a zip-based or unpacked artifact; a corrupted/incomplete Gradle dependency cache producing a non-jar file; a custom classpath configuration mistakenly including resource bundles or individual class files; Gradle version change altering how artifacts are materialized.

Related errors

• Build directory unknown to gradle: {}
• error patching [%s]: the jar does not contain [%s]
• Missing 'classesDirs' or 'classpath' property.
• Failed to build classpath URLs.
• Unknown license for license file: {}

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/b6a367f0c8f550c8. Report an issue: GitHub.