elastic/elasticsearch · error · IllegalArgumentException

expected zero arguments but was {}

Error message

expected zero arguments but was {}

What it means

JavaVersionChecker.main rejects any command-line arguments: the tool takes none. If args.length != 0 it throws IllegalArgumentException printing the supplied args. The tool exists only to verify java.specification.version >= 21 and exit non-zero otherwise.

Source

Thrown at distribution/tools/java-version-checker/src/main/java/org/elasticsearch/tools/java_version_checker/JavaVersionChecker.java:25

 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.tools.java_version_checker;

import java.util.Arrays;
import java.util.Locale;

/**
 * Java 8 compatible main to check the runtime version
 */
final class JavaVersionChecker {

    private JavaVersionChecker() {}

    public static void main(final String[] args) {
        // no leniency!
        if (args.length != 0) {
            throw new IllegalArgumentException("expected zero arguments but was " + Arrays.toString(args));
        }

        final int MIN_VERSION = 21;
        final int version;
        String versionString = System.getProperty("java.specification.version");
        if (versionString.equals("1.8")) {
            version = 8;
        } else {
            version = Integer.parseInt(versionString);
        }
        if (version >= MIN_VERSION) {
            return;
        }

        final String message = String.format(
            Locale.ROOT,
            "The minimum required Java version is %d; your Java version %d from [%s] does not meet that requirement.",
            MIN_VERSION,

View on GitHub (pinned to db6a809a66)

Solutions

1. Invoke java-version-checker with no arguments: java -jar java-version-checker.jar.
2. If your launcher needs flags, pass them to the JVM (-J args) or to the surrounding script, not as program args.
3. Confirm the Gradle 'java-version-checker' task is the one launching it (it always passes zero args).

Example fix

// before
java -jar java-version-checker.jar --check 21
// after
java -jar java-version-checker.jar

if (args != null && args.length != 0) throw new IllegalArgumentException("java-version-checker takes no args");
// invoke main with new String[0]

When it happens

Trigger: Invoking the java-version-checker jar/main with any CLI args (flags, --help, a path). The entrypoint is meant to be called by the Gradle/launcher shim with no arguments.

Common situations: Someone ran the checker jar manually with flags; a custom launcher script appended arguments; debugging hook passed extra args.

Related errors

• Task {} is not configured to use any clusters. Be sure to ca
• Can not use {} with {}
• Cannot specify more than one trust method (CA=%s, trustStore
• Task {} can't use test cluster from another project {}
• SSL trust has been configured, but [{}] is not a 'https' URL

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/e4ca66934abd2a88. Report an issue: GitHub.