oraios/serena · error · FileNotFoundError

typescript-language-server executable not found at {tsserver

Error message

typescript-language-server executable not found at {tsserver_executable_path}, something went wrong with the installation.

What it means

Thrown as FileNotFoundError when, after running the dependency installer for the typescript-language-server npm package, the expected tsserver executable still does not exist on disk at tsserver_executable_path. It indicates the automated installation step completed without producing the binary the server launch needs.

Source

Thrown at src/solidlsp/language_servers/typescript_language_server.py:332

            assert is_npm_installed, "npm is not installed or isn't in PATH. Please install npm and try again."

            # legacy unversioned dir reserved for INITIAL pair; any other version combination goes into a versioned subdir
            is_initial = (
                typescript_version == INITIAL_TYPESCRIPT_VERSION
                and typescript_language_server_version == INITIAL_TYPESCRIPT_LANGUAGE_SERVER_VERSION
            )
            ls_dirname = "ts-lsp" if is_initial else f"ts-lsp-{typescript_version}-{typescript_language_server_version}"
            tsserver_ls_dir = os.path.join(self._ls_resources_dir, ls_dirname)
            tsserver_executable_path = os.path.join(tsserver_ls_dir, "node_modules", ".bin", "typescript-language-server")

            if not os.path.exists(tsserver_executable_path):
                log.info(f"Typescript Language Server executable not found at {tsserver_executable_path}. Installing...")
                with LogTime("Installation of TypeScript language server dependencies", logger=log):
                    deps.install(tsserver_ls_dir)
                log.info("TypeScript language server dependencies installed successfully")

            if not os.path.exists(tsserver_executable_path):
                raise FileNotFoundError(
                    f"typescript-language-server executable not found at {tsserver_executable_path}, something went wrong with the installation."
                )
            return tsserver_executable_path

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

    def _get_language_id_for_file(self, relative_file_path: str) -> str:
        # JSX is parsed as TS without this, which silently truncates symbol
        # ranges at the first multi-line JSX expression.
        if relative_file_path.endswith(".tsx"):
            return "typescriptreact"
        if relative_file_path.endswith(".jsx"):
            return "javascriptreact"
        return self.language_id

    def _create_base_initialize_params(self) -> dict:
        initialize_params = {

View on GitHub (pinned to 7fcbca7e62)

Solutions

Delete the typescript language server install directory and retry, letting deps.install run fresh.
Run the npm install manually (npm install -g typescript typescript-language-server) and check npm/network errors.
Verify network/proxy/registry settings (npm config get registry; corporate proxy env vars).
Check disk space and directory write permissions for the install location.
If a global install exists, configure ls_path/ls_specific_settings to point at it and bypass auto-install.

Example fix

// before: relying on auto-install that fails behind a proxy
ls = SolidLSP("ts", "/repo")
// after: pre-install and point the server at the binary
// $ npm install -g typescript typescript-language-server
settings = {"ls_specific_settings": {"typescript": {"ls_path": "/usr/local/bin/typescript-language-server"}}}
ls = SolidLSP("ts", "/repo", settings)

Defensive patterns

Strategy: try-catch

Validate before calling

import os, shutil
if not (os.path.exists(expected_tsserver_path) or shutil.which("typescript-language-server")):
    # pre-install before constructing the server
    subprocess.run(["npm", "install", "-g", "typescript", "typescript-language-server"], check=True)

Type guard

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

Try / catch

try:
    ls = SolidLSP("typescript", repo_path)
except FileNotFoundError as e:
    if "typescript-language-server executable not found" in str(e):
        subprocess.run(["npm", "install", "-g", "typescript", "typescript-language-server"], check=True)
        ls = SolidLSP("typescript", repo_path)
    else:
        raise

Prevention

Pre-install language servers in your image/environment instead of relying on lazy auto-install.
Check `npm config get registry` and proxy env vars in CI before running.
Verify Node.js and npm are installed and on PATH.
Watch disk space and permissions in the install directory.

When it happens

Trigger: Calling SolidLSP for TypeScript triggers _get_or_install_core_dependency; deps.install(tsserver_ls_dir) runs but the tsserver executable is still absent when re-checked with os.path.exists.

Common situations: npm install silently failing behind a corporate proxy or with bad registry config; disk full; installing into a directory without write/execute permissions; partial installs left over from an interrupted run; native binary download blocked by antivirus.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/80ea3420d7107fca. Report an issue: GitHub.