oraios/serena · error · SolidLSPException

Could not parse java.home from '{java_exe}' output. This usu

Error message

Could not parse java.home from '{java_exe}' output. This usually means '{java_exe}' is not a valid JDK installation. First lines of output: {output.strip().splitlines()[:5]}

What it means

SolidLSPException thrown by _inspect_java when the output of 'java -XshowSettings:properties -version' contains no 'java.home = ...' line. This normally means the executable is not a real JDK/JVM, so the library cannot determine the true JDK home and aborts rather than guessing.

Source

Thrown at src/solidlsp/language_servers/eclipse_jdtls.py:660

            """
            try:
                # both -XshowSettings:properties and -version write to stderr by convention
                result = subprocess_run(
                    [java_exe, "-XshowSettings:properties", "-version"],
                    capture_output=True,
                    text=True,
                    timeout=15,
                    check=False,
                )
            except (OSError, subprocess.TimeoutExpired) as exc:
                raise SolidLSPException(f"Failed to run '{java_exe} -XshowSettings:properties -version': {exc}") from exc

            output = (result.stderr or "") + "\n" + (result.stdout or "")

            # parse java.home from "    java.home = /path/to/jdk"
            home_match = re.search(r"java\.home\s*=\s*(.+)", output)
            if not home_match:
                raise SolidLSPException(
                    f"Could not parse java.home from '{java_exe}' output. "
                    f"This usually means '{java_exe}' is not a valid JDK installation. "
                    f"First lines of output: {output.strip().splitlines()[:5]}"
                )
            real_home = home_match.group(1).strip()

            # parse major version from version line: 'openjdk version "21.0.2"' or 'java version "21.0.2"'
            version_match = re.search(r'version "(\d+)(?:\.\d+)*"', output)
            if not version_match:
                raise SolidLSPException(
                    f"Could not parse Java version from '{java_exe}' output. "
                    f"Required: JDK {JDTLS_MIN_JDK_VERSION}+. "
                    f"First lines of output: {output.strip().splitlines()[:5]}"
                )
            major = int(version_match.group(1))
            return real_home, major

        @classmethod

View on GitHub (pinned to 7fcbca7e62)

Solutions

Run '<java_exe> -XshowSettings:properties -version' manually and inspect the output
Replace the shim/stub with a real JDK and update java_home/JAVA_HOME accordingly
Reinstall the JDK if its output is corrupted
Set ls_specific_settings.java.java_home directly to a known-good JDK home to bypass PATH discovery

Example fix

// before
$ which java
/usr/bin/java  # distro stub that prints 'no java runtime present'
// after
java_home: /usr/lib/jvm/temurin-21-jdk-amd64  # real JDK home

Defensive patterns

Strategy: validation

Validate before calling

import subprocess, re
def java_home_parseable(java_exe: str) -> bool:
    r = subprocess.run([java_exe, "-XshowSettings:properties", "-version"],
                       capture_output=True, text=True, timeout=15)
    return bool(re.search(r"java\.home\s*=\s*(.+)", (r.stderr or "") + (r.stdout or "")))

Type guard

def looks_like_real_jvm(java_exe: str) -> bool:
    out = probe(java_exe)  # stderr+stdout of -XshowSettings:properties -version
    return "java.home" in out and "java.version" in out

Try / catch

try:
    ls = start_jdtls()
except SolidLSPException as e:
    if "Could not parse java.home" in str(e):
        replace_stub_with_real_jdk()  # e.g. install temurin-21 and set java_home
        ls = start_jdtls()
    else:
        raise

Prevention

Avoid shims/wrappers (sdkman, jabba, distro stubs) on PATH for service accounts
Set java_home explicitly to a real JDK home to bypass PATH discovery
On minimal Linux images, install a real JRE/JDK rather than relying on /usr/bin/java stub
Inspect the first output lines included in the error to identify the culprit binary

When it happens

Trigger: _resolve_system_jdk/_resolve_java -> _inspect_java where the combined stderr+stdout lacks a java.home property line - e.g. the 'java' resolved is a wrapper script, a JDK uninstaller stub, or prints unrelated text.

Common situations: PATH 'java' is a shim (sdkman/jabba wrapper misconfigured); a dummy stub binary like /usr/bin/java on minimal Linux without a real JVM; output locale/format changes breaking expectations; antivirus truncating output.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/7950308509090446. Report an issue: GitHub.