---
title: Restart Browser Helper
type: runbook
status: active
created: 2026-07-22
updated: 2026-07-22
verified_on: 2026-07-22
last_tested: 2026-07-22
confidence: high
tags: [runbook, browser, cua-driver, camofox]
sources: []
---

# Restart Browser Helper

## Purpose
Restart the computer-use browser stack that Hermes uses for web automation, screenshots, and VNC/noVNC access.

## Symptoms that match this runbook
- Browser screenshots are failing
- `cua-driver` MCP tools return errors
- VNC/noVNC is unreachable on `5901` / `6081`

## Prerequisites
- Display helper already running: `Xvfb :99`, x11vnc on `127.0.0.1:5901`, noVNC at `127.0.0.1:6081`
- `cua-driver` binary installed at `/home/hermes/.cua-driver/packages/releases/0.9.0-x86_64-unknown-linux-gnu/cua-driver`
- Browser VM/desktop helper is expected but not mandatory

## Procedure

### 1. Inspect current browser helpers
```bash
ps aux | grep -E "cua-driver serve|x11vnc|fluxbox|vnc-watcher" | grep -v grep
```

### 2. Stop cua-driver only
```bash
pkill -f "cua-driver serve"
```

### 3. Start cua-driver
```bash
/home/hermes/.local/bin/cua-driver serve
```
Run in background or a tmux/screen session if needed.

### 4. Verify ports remain available
```bash
nc -z 127.0.0.1 5901 && echo "x11vnc ok" || echo "x11vnc missing"
curl -s -o /dev/null -w "%{http_code}" http://127.0.0.1:6081/
```

### 5. Restart full browser VM stack only if step 4 fails
```bash
pkill -f "Xvfb :99"
pkill -f "x11vnc"
pkill -f "fluxbox"
/home/hermes/.local/bin/cua-driver serve
```

## Verification
- `cua-driver serve` process is present in `ps`
- `5901` and `6081` are reachable
- No zombie accumulation in browser/desktop processes

## Rollback
- If browser automation is not mission-critical, skip full VM restart and continue without it
- Do not stop gateway or dashboard unless necessary

## Notes
- This runbook assumes the standalone desktop helper is running separately from Hermes core
- The browser backend path can work without browser automation; this stack is optional depending on task

## Last tested
2026-07-22

## Related
- [[browser-backend]]
- [[restart-hermes]]