SeleniumHQ/selenium · error · OSError

Can't find java on system PATH. JRE is required to run the S

Error message

Can't find java on system PATH. JRE is required to run the Selenium server

What it means

Raised in `start()` when `self.java_path` is unset AND `shutil.which('java')` returns None, i.e. no `java` binary is discoverable on the system PATH. Running the Selenium server JAR requires a JRE, so without java the process cannot be built. It is an OSError.

Source

Thrown at py/selenium/webdriver/remote/server.py:189

        Latest version is downloaded unless specified.
        """
        args = ["--grid"]
        if version is not None:
            args.append(version)
        return SeleniumManager().binary_paths(args)["driver_path"]

    def start(self):
        """Start the server.

        Selenium Manager will detect the server location and download it if necessary,
        unless an existing server path was specified.
        """
        path = self.download_if_needed(self.version) if self.path is None else self.path

        java_path = self.java_path or shutil.which("java")
        if java_path is None:
            raise OSError("Can't find java on system PATH. JRE is required to run the Selenium server")

        command = [
            java_path,
            "-jar",
            path,
            "standalone",
            "--port",
            str(self.port),
            "--log-level",
            self.log_level,
            *self.args,
        ]
        if self.host is not None:
            command.extend(["--host", self.host])

        host = self.host if self.host is not None else "localhost"

        try:

View on GitHub (pinned to aa36b38e69)

Solutions

1. Install a JRE/JDK (e.g. apt-get install -y default-jre, or a temurin image).
2. Ensure java's bin directory is on PATH: `which java` must succeed in the same shell.
3. Alternatively set server.java_path to an absolute java binary you have verified exists.

Example fix

# before
# (no java installed)
server.start()

# after (Dockerfile)
# RUN apt-get update && apt-get install -y default-jre-headless
server.start()

import shutil
if server.java_path is None and shutil.which('java') is None:
    raise EnvironmentError('java/JRE not installed or not on PATH; install a JRE before start()')

When it happens

Trigger: Calling `server.start()` on a host/container that has no JDK/JRE installed, or where java is installed but its bin directory is not on PATH. Also when PATH is overridden/reset in the spawned environment (env setter) to exclude java's location.

Common situations: Minimal Docker images (python:slim) with no JVM. CI runners where java is installed under a toolchain manager (sdkman/asdf) that hasn't been activated for the shell. SSH sessions with a trimmed PATH.

Related errors

• Can't find java executable located at {java_path}
• log_level must be one of: {', '.join(levels)}
• env must be a mapping of environment variables
• Timed out waiting for Selenium server at {self.status_url}
• Selenium server isn't running

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/f6950e4c08968c95. Report an issue: GitHub.