oracle/graal · error · RuntimeException

%s specified by the %s system property is not readable

Error message

%s specified by the %s system property is not readable

What it means

HostedLibGraalClassLoader bootstraps the hosted libgraal classes from a module path given by the libgraal.module.path system property. parseModulePathEntry converts each entry to a Path and throws RuntimeException('%s specified by the %s system property is not readable') when Files.isReadable fails. The message names both the offending path and the property so the misconfiguration is immediately actionable.

Source

Thrown at compiler/src/jdk.graal.compiler.libgraal.loader/src/jdk/graal/compiler/libgraal/loader/HostedLibGraalClassLoader.java:200

                    "jdk.graal.compiler.options",
                    "jdk.graal.compiler.management",
                    "jdk.graal.compiler.libgraal",
                    "org.graalvm.truffle.compiler",
                    "com.oracle.graal.graal_enterprise")));

    static {
        ClassLoader.registerAsParallelCapable();
    }

    /**
     * Converts the module path entry {@code s} to a {@link Path}.
     *
     * @throws RuntimeException if {@code s} does not denote a readable path
     */
    Path parseModulePathEntry(String s) {
        Path path = Path.of(s);
        if (!Files.isReadable(path)) {
            throw new RuntimeException("%s specified by the %s system property is not readable".formatted(path, LIBGRAAL_MODULE_PATH_PROPERTY_NAME));
        }
        return path;
    }

    @SuppressWarnings("unused")
    public HostedLibGraalClassLoader() {
        // This loader delegates to the class loader that loaded its own class.
        super("LibGraalClassLoader", HostedLibGraalClassLoader.class.getClassLoader());

        try {
            /*
             * Access to jdk.internal.jimage classes is needed by this Classloader implementation.
             */
            var javaBaseModule = Object.class.getModule();
            Modules.addExports(javaBaseModule, "jdk.internal.jimage", HostedLibGraalClassLoader.class.getModule());

            /*
             * The classes that will get loaded by this loader require access to several internal

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Verify each entry exists and is readable: Files.isReadable(Path.of(entry)) before JVM launch.
2. Fix the property value: correct absolute paths, proper path-separator (; vs :), and no stray quotes/spaces.
3. Grant read permission (chmod/chmod +r, or adjust the service user's access) on the module file/directory.
4. Point libgraal.module.path at the modules shipped with your installed GraalVM distribution.

Example fix

# before
java -Dlibgraal.module.path=/opt/graalvm/libgraal:/typo/missing ...
# after (verify first)
ls /opt/graalvm/libgraal && java -Dlibgraal.module.path=/opt/graalvm/libgraal ...

// Pre-flight check before JVM launch (or in a launcher script)
for (String entry : System.getProperty("libgraal.module.path", "").split(File.pathSeparator)) {
    if (!entry.isEmpty() && !Files.isReadable(Path.of(entry))) {
        throw new RuntimeException("fix path: " + entry);
    }
}

When it happens

Trigger: Starting with -Dlibgraal.module.path=<entries> where an entry is a non-existent file/directory, a path with no read permission, or a typo'd/garbled path (bad quoting, wrong separator).

Common situations: Deploying to an environment where the libgraal module dir moved or has restrictive permissions; CI copying configs with stale absolute paths; shell quoting issues on Windows/Unix separators.

Related errors

• Use of %s is only supported in jargraal
• Given URI '%s' cannot be expressed as URL.
• Could not find option %s
• Class not found for polyglot type conversion handler: {}
• nargs not allowed

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/4f4c1d5a16b33696. Report an issue: GitHub.