HMCL-dev/HMCL · error · IOException

Missing Java version

Error message

Missing Java version

What it means

JavaInfo.fromReleaseFile() requires the JAVA_VERSION property from the release file to determine the Java version string. When the property is absent or null, it throws IOException("Missing Java version") — HMCL cannot report or compare the runtime's version without it.

Solutions

1. Use a complete JDK/JRE distribution whose release file contains JAVA_VERSION
2. Regenerate the jlink image with --release-info or copy JAVA_VERSION into the release file
3. Point the Java scan at the real java executable's installation directory, not a wrapper directory
4. Catch the IOException during scanning and mark the Java installation as unknown/invalid

Properties rel = new Properties();
rel.load(Files.newInputStream(javaHome.resolve("release")));
if (rel.getProperty("JAVA_VERSION") == null) {
    skipThisJavaInstallation(); // will otherwise throw
}

try {
    JavaInfo info = JavaInfo.fromReleaseFile(javaHome);
} catch (IOException e) {
    markJavaUnknownVersion(javaHome); // fallback: probe `java -version`
}

When it happens

Trigger: Reading a release file that lacks the JAVA_VERSION entry entirely (empty properties, minimal jlink/custom runtime image, or a truncated/corrupted release file).

Common situations: Custom jlink runtime images built without jdeps/release metadata; hand-crafted release files; some old or vendor-stripped JREs; a release file actually pointing to a directory that isn't a Java installation at all.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• Unknown operating system:
• Artifact name is malformed
• Bad Build-Number
• Candidates
• Cannot parse the version of

AI-assisted analysis of HMCL-dev/HMCL@24702dc5a0 (2026-09-10). Data as JSON: /api/errors/322984a399dfc47f. Report an issue: GitHub.

Appendix: source

Thrown at HMCLCore/src/main/java/org/jackhuang/hmcl/java/JavaInfo.java:83

        String osName = properties.get("OS_NAME");
        String osArch = properties.get("OS_ARCH");
        String vendor = properties.get("IMPLEMENTOR");

        OperatingSystem os = "".equals(osName) && "OpenJDK BSD Porting Team".equals(vendor)
                ? OperatingSystem.FREEBSD
                : OperatingSystem.parseOSName(osName);

        Architecture arch = Architecture.parseArchName(osArch);
        String javaVersion = properties.get("JAVA_VERSION");

        if (os == OperatingSystem.UNKNOWN)
            throw new IOException("Unknown operating system: " + osName);

        if (arch == Architecture.UNKNOWN)
            throw new IOException("Unknown architecture: " + osArch);

        if (javaVersion == null)
            throw new IOException("Missing Java version");

        return new JavaInfo(Platform.getPlatform(os, arch), javaVersion, vendor);
    }

    public static <F, E extends ArchiveEntry> JavaInfo fromArchive(ArchiveFileTree<F, E> tree) throws IOException {
        if (tree.getRoot().getSubDirs().size() != 1 || !tree.getRoot().getFiles().isEmpty())
            throw new IOException();

        ArchiveFileTree.Dir<E> jdkRoot = tree.getRoot().getSubDirs().values().iterator().next();
        E releaseEntry = jdkRoot.getFiles().get("release");
        if (releaseEntry == null)
            throw new IOException("Missing release file");

        JavaInfo info;
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(tree.getInputStream(releaseEntry), StandardCharsets.UTF_8))) {
            info = JavaInfo.fromReleaseFile(reader);
        }

View on GitHub (pinned to 24702dc5a0)