[BUG] Browser does not launch on Windows

[1827marketing]

What version of eigent are you using?

0.0.85

System information

Windows 11

Problem description

Summary

On Windows (packaged Desktop App), the backend endpoint that opens the Electron “login browser” can fail with:

FileNotFoundError: [WinError 2] The system cannot find the file specified even when npx works in an interactive terminal.

Symptoms / logs

Backend logs show it attempting to launch:

Electron args: ['npx', 'electron', ... 'electron_browser.cjs', ...] and then failing at subprocess.Popen(...) / Windows CreateProcess with [WinError 2].

Root cause (likely)

open_browser_login() in backend/app/controller/tool_controller.py invokes npx by name:

subprocess.Popen(["npx", "electron", ...])

In the packaged app context, the backend process environment may not inherit the user’s PATH as expected (and Windows process creation uses CreateProcess resolution, not PowerShell command resolution). As a result, npx may be unavailable even though it’s present/working in a user shell.

This is especially brittle on Windows because:

• PowerShell can resolve npx differently (e.g., npx.ps1) than CreateProcess can.
• A packaged Electron app may run with a different environment than an interactive terminal.
• Eigent already appears to provide an internal wrapper at ~/.eigent/bin/npx.cmd, but the backend doesn’t use it explicitly.

log

PS C:\Users\IanKirk> C:\Users\IanKirk\AppData\Local\Programs\Eigent\Eigent.exe
PS C:\Users\IanKirk>
08:39:20.657 > [PROXY] No proxy configured
try port 9222

DevTools listening on ws://127.0.0.1:9222/devtools/browser/bf4847cc-44a3-4faa-88cb-d63f79d7e40d
[info] [MAIN] Waiting for profile initialization...
[info] [CDP BROWSER] Created CDP profile directory at C:\Users\IanKirk.eigent\browser_profiles\cdp_profile_9222
[info] [CDP BROWSER] Chrome DevTools Protocol enabled on port 9222
[info] [CDP BROWSER] CDP profile directory: C:\Users\IanKirk.eigent\browser_profiles\cdp_profile_9222
[info] [STORAGE] Main app userData: C:\Users\IanKirk\AppData\Roaming\eigent
[info] [MAIN] Profile initialization completed
[info] [ANTI-FINGERPRINT] User Agent set for all sessions
[info] [PROTOCOL] Registered localfile protocol on both default and main_window sessions
[info] .eigent directory structure ensured
[info] Seeded default skills to ~/.eigent/skills from C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\example-skills
[info] [PROJECT BROWSER WINDOW] Creating BrowserWindow which will start Chrome with CDP on port 9222
[info] [PROJECT BROWSER WINDOW] Current user data path: C:\Users\IanKirk\AppData\Roaming\eigent
[info] [PROJECT BROWSER WINDOW] Command line switch user-data-dir: C:\Users\IanKirk.eigent\browser_profiles\cdp_profile_9222
[info] [COOKIE SYNC] No tool_controller partition found, WebView will start fresh
[info] [PROJECT BROWSER] Creating WebViews with partition: persist:user_login
[info] [PROJECT BROWSER] WebViewManager initialized with webviews
Current version: 0.0.85
Update config path: undefined
User data path (where config lives): C:\Users\IanKirk\AppData\Roaming\eigent
Checking for update
[info] Pre-checking if dependencies need to be installed...
[info] [PRE-CHECK] Prebuilt dependencies found, skipping installation check
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\uv.exe
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\bun.exe
[info] Installation check result: {
needsInstallation: false,
versionExists: true,
versionMatch: true,
uvExists: true,
bunExists: true,
installationCompleted: false,
venvExists: true,
venvPath: 'C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\venv'
}
[info] Installation already complete - letting useInstallationSetup handle state transitions
Update for version 0.0.85 is not available (latest version: 0.0.85, downgrade is disallowed).
checkForUpdatesAndNotify called, downloadPromise is null
[info] Window content loaded, starting dependency check immediately...
[info] Window shown after content loaded
[info] Window is ready, processing queued protocol URLs...
Checking for update
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\uv.exe
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\bun.exe
Update for version 0.0.85 is not available (latest version: 0.0.85, downgrade is disallowed).
checkForUpdatesAndNotify called, downloadPromise is null
[info] [DEPS INSTALL] Prebuilt dependencies found, skipping installation
[info] [DEPS INSTALL] Using prebuilt dependencies, creating version file
[info] [DEPS INSTALL] version file updated { currentVersion: '0.0.85' }
[info] [DEPS INSTALL] Using prebuilt terminal venv: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\terminal_venv
[info] [DEPS INSTALL] Dependency Success: Using prebuilt dependencies
[info] [DEPS INSTALL] Sent install-dependencies-complete event to frontend
[info] [DEPS INSTALL] Starting backend...
[info] Checking and starting backend service...
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\uv.exe
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\bun.exe
[info] Tool installed, starting backend service...
start fastapi
[info] Using prebuilt binary: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\bin\uv.exe
[info] [VENV] Created uv_python symlink: C:\Users\IanKirk.eigent\uv_python
[info] [VENV] Backend venv already at C:\Users\IanKirk.eigent\venvs\backend-0.0.85 (v0.0.85)
userData C:\Users\IanKirk\AppData\Roaming\eigent
Using venv path: C:\Users\IanKirk.eigent\venvs\backend-0.0.85
try port 5001
[info] Found available port: 5001
[info] Backend service started successfully { port: 5001 }
[info] [VENV] Using prebuilt Python: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\uv_python
[info] [VENV] Backend venv already at C:\Users\IanKirk.eigent\venvs\backend-0.0.85 (v0.0.85)
[info] Backend SERVER_URL resolved to: https://dev.eigent.ai/api (source: default)
[info] [VENV] Terminal venv already at C:\Users\IanKirk.eigent\venvs\terminal_base-0.0.85 (v0.0.85)
[info] Spawning backend process: C:\Users\IanKirk.eigent\venvs\backend-0.0.85\Scripts\python.exe -m uvicorn main:api --port 5001 --loop asyncio
[info] Backend working directory: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\backend
[info] Python test output: Python OK
[info] Backend process spawned with PID: 18140
[info] Backend process still running after 1s with PID 18140
[info] Starting backend health check polling...
[info] BACKEND: 2026-02-26 08:39:29,902 - main - INFO - Starting Eigent Multi-Agent System API
2026-02-26 08:39:29,902 - main - INFO - Python encoding: utf-8
2026-02-26 08:39:29,902 - main - INFO - Environment: development
[info] BACKEND: 2026-02-26 08:39:29,902 - main - INFO - Loading routers with prefix: ''
2026-02-26 08:39:29,903 - router - INFO - Registered Health router: 1 routes - Health check endpoint for service readiness
[info] BACKEND: 2026-02-26 08:39:29,913 - router - INFO - Registered chat router: 9 routes - Chat session management, improvements, and human interactions
[info] BACKEND: 2026-02-26 08:39:29,918 - router - INFO - Registered model router: 1 routes - Model validation and configuration
[info] BACKEND: 2026-02-26 08:39:29,918 - router - INFO - Registered task router: 5 routes - Task lifecycle management (start, stop, update, control)
[info] BACKEND: 2026-02-26 08:39:29,925 - router - INFO - Registered tool router: 12 routes - Tool installation and management
2026-02-26 08:39:29,925 - router - INFO - Total routers registered: 5
2026-02-26 08:39:29,925 - main - INFO - All routers loaded successfully
[info] BACKEND: 2026-02-26 08:39:29,927 - main - INFO - Application initialization completed successfully
INFO: Started server process [2688]
INFO: Waiting for application startup.
[info] BACKEND: 2026-02-26 08:39:29,927 - main - INFO - PID write task created
2026-02-26 08:39:29,927 - app.utils.telemetry.workforce_metrics - INFO - Langfuse credentials not found, telemetry disabled
2026-02-26 08:39:29,927 - main - INFO - Telemetry tracer provider initialized
[info] BACKEND: INFO: Application startup complete.
[info] BACKEND: INFO: Uvicorn running on http://127.0.0.1:5001 (Press CTRL+C to quit)
[info] BACKEND: 2026-02-26 08:39:29,941 - main - INFO - PID file written: 2688
[info] Backend health check passed after 12 attempts
[info] Backend is ready, notifying frontend...
[info] BACKEND: 2026-02-26 08:39:41,709 - tool_controller - INFO - [COOKIES CHECK] Tool controller user_data_dir: C:\Users\IanKirk/.eigent/browser_profiles\profile_user_login
[info] BACKEND: 2026-02-26 08:39:58,365 - tool_controller - INFO - Creating browser session user_login with profile at: C:\Users\IanKirk/.eigent/browser_profiles\profile_user_login
[info] BACKEND: 2026-02-26 08:40:00,420 - tool_controller - INFO - [PROFILE USER LOGIN] Launching Electron browser with CDP on port 9223
2026-02-26 08:40:00,420 - tool_controller - INFO - [PROFILE USER LOGIN] Working directory: C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources
[info] BACKEND: 2026-02-26 08:40:00,420 - tool_controller - INFO - [PROFILE USER LOGIN] userData path: C:\Users\IanKirk/.eigent/browser_profiles\profile_user_login
2026-02-26 08:40:00,422 - tool_controller - INFO - [PROFILE USER LOGIN] Electron args: ['npx', 'electron', 'C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\backend\app\controller\electron_browser.cjs', 'C:\Users\IanKirk/.eigent/browser_profiles\profile_user_login', '9223', 'https://www.google.com']
[error] BACKEND: 2026-02-26 08:40:00,429 - tool_controller - ERROR - Failed to open Electron browser for login: [WinError 2] The system cannot find the file specified
Traceback (most recent call last):
File "C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\backend\app\controller\tool_controller.py", line 740, in open_browser_login
process = subprocess.Popen(
^^^^^^^^^^^^^^^^^
File "C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\uv_python\cpython-3.11.11-windows-x86_64-none\Lib\subprocess.py", line 1026, in init
self._execute_child(args, executable, preexec_fn, close_fds,
File "C:\Users\IanKirk\AppData\Local\Programs\Eigent\resources\prebuilt\uv_python\cpython-3.11.11-windows-x86_64-none\Lib\subprocess.py", line 1538, in _execute_child
hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [WinError 2] The system cannot find the file specified
[info] BACKEND: 2026-02-26 08:40:00,970 - tool_controller - INFO - [COOKIES CHECK] Tool controller user_data_dir: C:\Users\IanKirk/.eigent/browser_profiles\profile_user_login
[info] BACKEND: 2026-02-26 08:40:00,977 - tool_controller - INFO - [COOKIES CHECK] Tool controller user_data_dir: C:\Users\IanKirk/.eigent/browser_profiles\profile_user_login
[info] before-quit
[info] quit python_process.pid: 18140
Webview 1 destroyed successfully
Webview 2 destroyed successfully
Webview 4 destroyed successfully
Webview 3 destroyed successfully
Webview 6 destroyed successfully
Webview 8 destroyed successfully
Webview 5 destroyed successfully
Webview 7 destroyed successfully
[info] window-all-closed
[info] before-quit
[info] quit python_process.pid: 18140
[info] Cleaning up Python process and all children { pid: 18140 }
[info] Cleaning up Python process and all children { pid: 18140 }
[info] Successfully sent SIGTERM to process tree
[error] Failed to clean up process tree with SIGTERM: Error: Command failed: taskkill /pid 18140 /T /F
ERROR: The process with PID 21964 (child process of PID 18140) could not be terminated.
Reason: The operation attempted is not supported.
ERROR: The process with PID 2688 (child process of PID 18140) could not be terminated.
Reason: There is no running instance of the task.
ERROR: The process with PID 18140 (child process of PID 19692) could not be terminated.
Reason: The operation attempted is not supported.

at genericNodeError (node:internal/errors:984:15)
at wrappedFn (node:internal/errors:538:14)
at ChildProcess.exithandler (node:child_process:422:12)
at ChildProcess.emit (node:events:518:28)
at maybeClose (node:internal/child_process:1104:16)
at ChildProcess._handle.onexit (node:internal/child_process:304:5)

[error] Failed to force kill process tree: Error: Command failed: taskkill /pid 18140 /T /F
ERROR: The process "18140" not found.

at genericNodeError (node:internal/errors:984:15)
at wrappedFn (node:internal/errors:538:14)
at ChildProcess.exithandler (node:child_process:422:12)
at ChildProcess.emit (node:events:518:28)
at maybeClose (node:internal/child_process:1104:16)
at ChildProcess._handle.onexit (node:internal/child_process:304:5)

[info] Attempting to kill process on port: 5001
[error] Failed to kill process on port 5001: Error: Command failed: netstat -ano | findstr LISTENING | findstr :5001

at genericNodeError (node:internal/errors:984:15)
at wrappedFn (node:internal/errors:538:14)
at ChildProcess.exithandler (node:child_process:422:12)
at ChildProcess.emit (node:events:518:28)
at maybeClose (node:internal/child_process:1104:16)
at ChildProcess._handle.onexit (node:internal/child_process:304:5)

[info] All cleanup completed, exiting...

Additional context

Suggested direction

Any of the following would make this robust:

Resolve npx deterministically

• Prefer an absolute path to Eigent’s own wrapper (~/.eigent/bin/npx.cmd) when present.
• Otherwise fallback to shutil.which("npx") / which("npx.cmd").

Windows-safe invocation

• When invoking .cmd/batch wrappers, use cmd.exe /c ... (or shell=True with care) so .cmd execution is reliable.

Pass a known-good PATH into the subprocess

• Ensure the spawned Electron login browser inherits a PATH that includes the wrapper directory (e.g., ~/.eigent/bin) regardless of how the backend was launched.

Architectural alternative (often cleanest in desktop apps)

• Launch the login browser from the Electron main process (which already controls environment setup), rather than from the Python backend, and communicate status back to the backend via IPC/HTTP. This avoids environment mismatch entirely.

Local workaround confirmed

I found that just adding to the user PATH wasn't enough so I patched the code. With Github Copilot's help I edited tool_controller.py to get it to work on my system. My patched tool_controller.py is attached for reference, but I doubt that it is production-ready.

tool_controller.py

[1827marketing]

Browser Agent and Notion MCP Server are affected by the same issue

I have started testing Eigent on my Windows Laptop now that I have patched the Login Browser issue. I found that the build-in Browser Agent was constantly failing for the same reason that the browser would not load before. The notes below are Claude/CoPilot generated, explaining the npx path issues and possible fixes.

Additional affected code paths beyond Login Browser

The [WinError 2] / CreateProcess failure reported here for the login browser also affects at least two other code paths that use the same bare "npx" invocation pattern. I wanted to document these for the engineering team since they share the same root cause and should ideally be fixed together.

Root cause recap

On Windows, subprocess.Popen(["npx", ...]) without shell=True calls the Win32 CreateProcess API directly. CreateProcess cannot execute .cmd or .bat files — only .exe binaries. Even though the Electron main process in electron/main/init.ts correctly prepends ~/.eigent/bin (containing npx.cmd) and the nodejs_wheel/bin directory to PATH before spawning the backend, the Python subprocess calls still fail because CreateProcess finds npx.cmd but doesn't know how to execute it.

This also means setting User Environment Variables (PATH) will not fix the issue — the PATH is already correct at the process level. The problem is the Win32 API limitation with .cmd files.

Affected code path 1: Login Browser (the reported issue)

File: backend/app/controller/tool_controller.py — open_browser_login()

Python

electron_cmd = "npx"
electron_args = [electron_cmd, "electron", electron_script_path, ...]

process = subprocess.Popen(
    electron_args,
    cwd=app_dir,
    ...
    # No shell=True
)

This is the failure described in the original report.

Affected code path 2: Browser Agent WebSocket server

File: backend/app/agent/toolkit/hybrid_browser_toolkit.py — WebSocketBrowserWrapper.start()

Python

async def start(self):
    # Simply use the parent implementation which uses system npm/node
    self._ensure_local_no_proxy()
    await super().start()

This calls BaseWebSocketBrowserWrapper.start() from the camel library, which spawns an npm/npx/node subprocess to start the TypeScript WebSocket server that bridges CDP browser control. On a packaged Windows install, this fails with the same CreateProcess / .cmd resolution issue. This means the built-in Browser Agent used during tasks (not just the login browser) cannot launch its WebSocket bridge on Windows.

Affected code path 3: Notion MCP Toolkit

File: backend/app/agent/toolkit/notion_mcp_toolkit.py

Python

config_dict = {
    "mcpServers": {
        "notionMCP": {
            "command": "npx",
            "args": ["-y", "mcp-remote", "https://mcp.notion.com/mcp"],
            ...
        }
    }
}

Hardcodes "npx" as the MCP server command. The MCPToolkit from camel will attempt to spawn this, hitting the same Windows issue.

What the Electron side already does correctly

electron/main/init.ts lines 313–335 in startBackend() already:

1. Calls findNodejsWheelNpmPath(venvPath) to locate ~/.eigent/bin (containing npx.cmd/npm.cmd wrappers)
2. Calls findNodejsWheelBinPath(venvPath) to locate nodejs_wheel/bin (containing node.exe)
3. Prepends both to PATH in the environment passed to the backend process

So the backend does inherit a PATH with the correct directories. The problem is exclusively that CreateProcess cannot run .cmd files without going through cmd.exe.

Suggested fix direction

All three code paths need one or both of:

1. shell=True (or cmd.exe /c wrapping) when invoking .cmd files on Windows — so cmd.exe handles the .cmd → script execution
2. Resolve npx to an absolute path using shutil.which("npx") (which correctly finds .cmd extensions on Windows) and then use shell=True if the resolved path ends in .cmd

A shared utility (e.g., backend/app/utils/node_paths.py) could centralise this logic since the pattern repeats in at least three places. Something like:

Python

def resolve_npx() -> str:
    """Resolve npx to absolute path, preferring ~/.eigent/bin wrapper."""
    eigent_npx = os.path.join(os.path.expanduser("~/.eigent/bin"), 
                               "npx.cmd" if sys.platform == "win32" else "npx")
    if os.path.isfile(eigent_npx):
        return eigent_npx
    found = shutil.which("npx")
    return found or "npx"

def subprocess_needs_shell(cmd: str) -> bool:
    """True if cmd is a .cmd/.bat that needs shell=True on Windows."""
    return sys.platform == "win32" and cmd.lower().endswith((".cmd", ".bat"))

For the camel library dependency (BaseWebSocketBrowserWrapper and MCPToolkit), the fix may need to either:

• Override the process-spawning method in Eigent's subclass to add shell=True on Windows, or
• Ensure ~/.eigent/bin is on os.environ["PATH"] at the Python process level (it currently is, but the camel library itself would also need to use shell=True internally)

[nitpicker55555]

@1827marketing Can you check this #1397 ?

[1827marketing]

Hi @nitpicker55555 thanks for working on this so quickly. Apologies but I don't have the environment or qualifications to be able to check your work.

[nitpicker55555]

@1827marketing hi～ https://github.com/eigent-ai/eigent/actions/runs/22575516296/artifacts/5720945508 this is the download link for this fix, can you check this?