Chrome-Error Protocol Source Map Issue in Web Development

Problem Statement

When running applications in Chrome (via frameworks like Flutter, React, or Vite), you may encounter the error:
Could not read source map for chrome-error://chromewebdata/: Unexpected 503 response from chrome-error://chromewebdata/neterror.rollup.js.map: Unsupported protocol "chrome-error:"

This typically occurs when:

• Debugging in VS Code with configured launch tasks
• The development server isn't running before launching the debugger
• Corrupted or misconfigured IDE settings exist
• Required entry files (like index.html) are missing

The error indicates Chrome's developer tools are attempting to access restricted internal files (chrome-error:// protocol), blocking source map loading.

---

Solutions

Here are verified approaches to resolve the issue:

1. Run the Development Server Manually (Quick Fix)

# Run this BEFORE launching your debugger:
npm start    # Node.js projects
# OR
flutter run -d chrome  # Flutter projects

After the server starts, launch debugging (F5).
Why it works: Ensures Chrome loads your application files first instead of internal error pages.

2. Configure VS Code for Automatic Server Start

Update .vscode/launch.json to run your development server as a pre-debug task:

{
  "version": "0.2.0",
  "configurations": [
    {
      "preLaunchTask": "npm: dev",  // Matches scripts in package.json
      "type": "chrome",
      "request": "launch",
      "name": "Launch Chrome",
      "url": "http://localhost:5173",  // Your dev server URL
      "webRoot": "${workspaceFolder}"
    }
  ]
}

3. Verify Critical File Structure

Missing core files trigger Chrome's error page:

• Ensure index.html exists at project root
• Confirm it loads your entry script:

  <!-- Example in React/Vite: -->
  <script type="module" src="/src/main.tsx"></script>

4. Reset VS Code Configuration

Delete your .vscode folder (temporarily) to eliminate misconfigurations:

1. Close VS Code
2. Delete the .vscode directory in your project
3. Reopen the project and regenerate configs if needed

---

Explanation of Core Fixes

• Source Map Loading Failure: Chrome blocks access to chrome-error:// resources during debugging.
• Server Timing Issues: Debuggers launched before the development server cause Chrome to load error pages as the initial documents.
• VS Code Automation: The preLaunchTask ensures your server is ready before Chrome launches.
• File Integrity Checks: Missing index.html causes Chrome to fall back to error pages, triggering the source map issue.

For Flutter Projects

Use this VS Code task to automate flutter run:

// .vscode/launch.json
{
  "configurations": [
    {
      "preLaunchTask": "flutter: run -d chrome",
      "type": "dart",
      "request": "launch"
    }
  ]
}

Common Pitfall

After setting up tasks.json, VS Code may prompt:
"Your build task may have problems..." → Click Debug Anyway to force execution.