$http request returns 404 Not Found

A 404 Not Found error in an $http request means the requested resource does not exist on the server. This can occur due to incorrect URLs, server-side issues, or misconfigurations.

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1. Why Does a 404 Error Occur?

A 404 error happens when:

• The requested URL is incorrect or does not exist.
• The API endpoint has changed or moved.
• The backend server is down or misconfigured.
• The API requires authentication (401 Unauthorized instead of 404).
• The API is not accessible from the client due to routing issues.

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2. Debugging a 404 Error Step-by-Step

Step 1: Check the URL

Ensure the URL is correct.

Example request using $http in AngularJS:

$http.get('https://api.example.com/data')
  .then(response => console.log(response.data))
  .catch(error => console.error('Error:', error));

If the API moved from /data to /v2/data, the request will fail with a 404.

Fix: Update the URL.

$http.get('https://api.example.com/v2/data')

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Step 2: Test the API Manually

• Open the API URL in the browser (for GET requests).
• Use Postman or cURL: curl -X GET https://api.example.com/data
• If it returns 404, check if the API still exists.

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Step 3: Check API Endpoint on the Server

If you control the API, verify that it handles the requested route.

Node.js Express Example

app.get('/data', (req, res) => {
  res.json({ message: 'Success' });
});

Fix: Ensure the API has the correct route and method.

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Step 4: Debug Routing Issues

If using path parameters, ensure they are correct.

Example of incorrect request:

$http.get('https://api.example.com/user') //  Missing user ID

Correct request:

$http.get('https://api.example.com/user/123') //  Include user ID

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Step 5: Handle AngularJS Route Configuration

If using AngularJS routing, a missing route might cause 404 errors.

Example of AngularJS route configuration:

app.config(function($routeProvider) {
  $routeProvider
    .when('/home', {
      templateUrl: 'home.html',
      controller: 'HomeController'
    })
    .otherwise({
      redirectTo: '/home' //  Redirect unknown routes
    });
});

Fix: Ensure the route is properly defined.

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Step 6: Check Backend Server

• Verify the server is running.
• Restart the server if needed: shCopyEditpm2 restart all
• Check the server logs: tail -f /var/log/nginx/error.log

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Step 7: Check for API Authentication

Some APIs require authentication and may return 404 instead of 401.

Example: API request missing token

$http.get('https://api.example.com/data', {
  headers: { 'Authorization': 'Bearer INVALID_TOKEN' }
});

Fix: Use a valid token.

$http.get('https://api.example.com/data', {
  headers: { 'Authorization': 'Bearer YOUR_ACCESS_TOKEN' }
});

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Step 8: Fixing CORS Issues

If the API is blocked due to CORS, it might return a misleading 404.

Fix: Allow CORS on the server.

app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST');
  next();
});

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3. Final Thoughts

A 404 Not Found error in $http means the resource is missing or inaccessible. Fix it by:

• Checking the URL.
• Testing the API manually.
• Debugging routing issues.
• Ensuring authentication is correct.
• Handling CORS restrictions.