oracle/graal · error · IllegalArgumentException

Unsupported java version:

Error message

Unsupported java version: 

What it means

JavaVersion.forVersion(int) normalizes a Java feature version number (e.g. 8, 21, 26; LATEST_SUPPORTED is 26). Any value below 1 — zero or negative — is rejected with IllegalArgumentException 'Unsupported java version: <n>'.

Source

Thrown at espresso-shared/src/com.oracle.truffle.espresso.classfile/src/com/oracle/truffle/espresso/classfile/JavaVersion.java:90

        public boolean contains(JavaVersion version) {
            return version.inRange(low, high);
        }
    }

    public static final JavaVersion HOST_VERSION = forVersion(Runtime.version());

    public static final int LATEST_SUPPORTED = 26;
    public static final int LATEST_SUPPORTED_CLASSFILE = ClassfileParser.JAVA_26_VERSION;

    private final int version;

    JavaVersion(int version) {
        this.version = version;
    }

    public static JavaVersion forVersion(int version) {
        if (version < 1) {
            throw new IllegalArgumentException("Unsupported java version: " + version);
        }
        return new JavaVersion(version);
    }

    public static JavaVersion forVersion(String version) {
        int begin = 0;
        int end = version.length();
        if (version.startsWith("1.")) {
            begin = 2;
        }
        int firstDot = version.indexOf('.', begin);
        if (firstDot >= 0) {
            end = firstDot;
        }
        String normalizedVersion = version.substring(begin, end);
        try {
            int intVersion = Integer.parseInt(normalizedVersion);
            return forVersion(intVersion);

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Validate the int (>= 1) before calling forVersion and surface your own configuration error naming the source of the bad value
2. Trace where the 0/negative came from: usually a preceding parse failure left a default or sentinel

Example fix

// before
JavaVersion v = JavaVersion.forVersion(parsedVersion); // parsedVersion == 0 from failed parse

// after
if (parsedVersion < 1) throw new IllegalArgumentException("Bad version from config: " + raw);
JavaVersion v = JavaVersion.forVersion(parsedVersion);

if (version < 1) throw new IllegalArgumentException("version must be >= 1, got " + version);

When it happens

Trigger: Passing 0 or a negative int, often the result of a failed parse or an uninitialized field (0 default), or arithmetic like version - 1 underflowing.

Common situations: Parsing '-Djava.version' style strings when a custom parse already returned a sentinel 0/-1; an int field left at its default 0 before configuration; unit tests exercising edge values.

Related errors

• Unsupported java version: {} ({})
• Cannot compare {JavaLangRuntimeVersion.__name__} to {type(ot
• Out of scratch registers: %s
• No ClassConstant at constant pool index ${cpi}
• Authority component present

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/4dab4cb7863bbab5. Report an issue: GitHub.