oracle/graal · error · AssertionError

Could not execute {jdk.java}

Error message

Could not execute {jdk.java}

What it means

mx probes the JDK for JVMCI support by running 'java -XX:+UnlockExperimentalVMOptions -XX:+PrintFlagsFinal -version'. A non-zero return code (java not executable, broken JDK, or unsupported flags) causes AssertionError 'Could not execute <java path>'.

Source

Thrown at sdk/mx.sdk/mx_sdk_vm.py:600

            _base_jdk_final = _base_jdk_stage1
    return _base_jdk_final


def base_jdk_version(stage1=True):
    return base_jdk(stage1=stage1).javaCompliance.value

def get_jdk_version_for_profiles():
    jdk_version = mx.get_jdk().javaCompliance.value
    return '_LATEST' if jdk_version > 21 else jdk_version

def _probe_jvmci_info(jdk, attribute_name):
    if not hasattr(jdk, '.enables_jvmci_by_default'):
        out = mx.LinesOutputCapture()
        def sink(x):
            return x
        rc = mx.run([jdk.java, '-XX:+UnlockExperimentalVMOptions', '-XX:+PrintFlagsFinal', '-version'], out=out, err=sink, nonZeroIsFatal=False)
        if rc != 0:
            raise AssertionError(f"Could not execute {jdk.java}")
        enableJVMCI = False
        jvmciThreadsPerNativeLibraryRuntime = None
        for line in out.lines:
            if 'EnableJVMCI' in line and 'true' in line:
                enableJVMCI = True
            if 'JVMCIThreadsPerNativeLibraryRuntime' in line:
                m = re.search(r'JVMCIThreadsPerNativeLibraryRuntime *= *(\d+)', line)
                if not m:
                    mx.abort(f'Could not extract value of JVMCIThreadsPerNativeLibraryRuntime from "{line}"')
                jvmciThreadsPerNativeLibraryRuntime = int(m.group(1))
        setattr(jdk, '.enables_jvmci_by_default', enableJVMCI)
        setattr(jdk, '.jvmciThreadsPerNativeLibraryRuntime', jvmciThreadsPerNativeLibraryRuntime)
    return getattr(jdk, attribute_name)

def jdk_enables_jvmci_by_default(jdk):
    """
    Gets the default value for the EnableJVMCI VM option in `jdk`.
    """

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Run the probe command manually with the reported path: <jdk>/bin/java -XX:+UnlockExperimentalVMOptions -XX:+PrintFlagsFinal -version, and read its error.
2. Fix or reinstall the JDK, or point mx at a valid JDK via --java-home/JAVA_HOME (a full JDK, not a JRE).
3. Use a GraalVM-supported JDK version so the experimental flags exist.

Example fix

# before
export JAVA_HOME=/opt/jre11   # probe fails -> AssertionError

# after
export JAVA_HOME=/opt/jdk21
mx --java-home=/opt/jdk21 build

import subprocess, os
java = os.path.join(jdk_path, "bin", "java")
rc = subprocess.run([java, "-XX:+UnlockExperimentalVMOptions", "-XX:+PrintFlagsFinal", "-version"]).returncode
assert rc == 0, f"JDK probe failed (rc={rc}); fix or replace the JDK at {jdk_path}"

When it happens

Trigger: JAVA_HOME/jdk set to a broken, partial, or non-JVMCI-aware JDK; the java binary missing execute permission; a JDK too old/new such that the probe flags are rejected.

Common situations: Pointing mx at a JRE instead of a full JDK; truncated JDK extraction; docker images with a stripped java; switching JDKs mid-session with stale cached probe results.

Related errors

• Set the JVMCI_VERSION_CHECK environment variable to "ignore"
• Unexpected OS name: %s
• Neither {daCapoClasspathEnvVarName} variable nor {daCapoLibr
• The SPECJVM2008 environment variable was not specified.
• The SPECJBB2015 environment variable was not specified.

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/def92e91a52a0e3b. Report an issue: GitHub.