oraios/serena · error · FileNotFoundError

{LS_BIN_NAME} executable not found at {executable_path}; npm

Error message

{LS_BIN_NAME} executable not found at {executable_path}; npm install of {package_name}@{package_version} did not produce the expected binary.

What it means

Thrown as FileNotFoundError when npm installation of the vscode-html-languageserver package finishes but the expected LS binary (vscode-html-language-server) is not found at executable_path. It guards the launch path so the server is never started against a missing binary.

Source

Thrown at src/solidlsp/language_servers/vscode_html_language_server.py:104

                executable_path += ".cmd"

            if not os.path.exists(executable_path):
                expected_version = f"{package_name}@{package_version}"
                log.info("Installing %s for HTML language server...", expected_version)
                deps = RuntimeDependencyCollection(
                    [
                        RuntimeDependency(
                            id=package_name,
                            description=f"{package_name} (provides {LS_BIN_NAME})",
                            command=build_npm_install_command(package_name, package_version, npm_registry),
                            platform_id="any",
                        ),
                    ]
                )
                deps.install(install_dir)

            if not os.path.exists(executable_path):
                raise FileNotFoundError(
                    f"{LS_BIN_NAME} executable not found at {executable_path}; "
                    f"npm install of {package_name}@{package_version} did not produce the expected binary."
                )
            return executable_path

        def _create_launch_command(self, core_path: str) -> list[str]:
            return [core_path, "--stdio"]

    def _create_base_initialize_params(self) -> dict:
        initialize_params: dict = {
            "locale": "en",
            "capabilities": {
                "textDocument": {
                    "synchronization": {"didSave": True, "dynamicRegistration": True},
                    "completion": {"dynamicRegistration": True, "completionItem": {"snippetSupport": True}},
                    "definition": {"dynamicRegistration": True},
                    "references": {"dynamicRegistration": True},
                    "documentSymbol": {

View on GitHub (pinned to 7fcbca7e62)

Solutions

Remove install_dir and retry so deps.install performs a clean npm install.
Verify the pinned package_name@package_version actually publishes the expected binary (run npm ls / inspect package bin field).
Run the npm install manually in install_dir and read the npm output for the real failure.
Check network/proxy settings and disk/permission issues affecting the install directory.
Pre-install globally and configure ls_path to point at the existing binary.

Example fix

// before: pin a version whose binary layout changed
package_version = "1.4.0"
// after: pin a known-good version and pre-verify
// $ npm install -g @vscode/vscode-languageserver-node-html@1.5.1
package_version = "1.5.1"  // version confirmed to ship vscode-html-language-server bin

Defensive patterns

Strategy: try-catch

Validate before calling

import os
if not os.path.isfile(expected_html_ls_binary):
    subprocess.run(["npm", "install", "-g", package_name + "@" + package_version], check=True)
    assert os.path.exists(expected_html_ls_binary), "binary still missing after install"

Type guard

def is_executable_file(path: str) -> bool:
    return os.path.isfile(path) and os.access(path, os.X_OK)

Try / catch

try:
    ls = SolidLSP("html", repo_path)
except FileNotFoundError as e:
    if "executable not found" in str(e):
        shutil.rmtree(install_dir, ignore_errors=True)
        ls = SolidLSP("html", repo_path)  # clean reinstall
    else:
        raise

Prevention

Pin a package_version known to publish the expected binary and test it once in CI.
Perform a clean install (delete install_dir) after any interrupted run.
Pre-install globally and set ls_path rather than depending on runtime npm installs.
Validate network/proxy config before first launch.

When it happens

Trigger: _get_or_install_core_dependency runs deps.install(install_dir) for the html language server package, then the existence check for LS_BIN_NAME fails.

Common situations: Wrong package_version pinned that no longer ships the binary; npm failing silently behind a proxy; OS-specific bin layout differences (npm bin dir not where the code expects); partial or corrupted node_modules; permission problems in install_dir.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/6d52604026daf3e9. Report an issue: GitHub.