CORS Error in Angular – Quick Fix Guide

Introduction

The CORS (Cross-Origin Resource Sharing) Error is one of the most common issues Angular developers encounter when making HTTP requests to APIs hosted on different domains, ports, or protocols.

Browsers enforce the Same-Origin Policy to protect users from malicious websites, and if the target server is not configured to allow cross-origin requests, Angular applications will display a CORS error instead of receiving the expected response. In this tutorial, you will clear the concept of CORS error in Angular

What is a CORS Error?

CORS means Cross-Origin Resource Sharing. A CORS error happens when a browser blocks a request from your Angular application to another domain.

Example:


Angular App → http://localhost:4200
API Server → http://localhost:3000

Explanation:

The browser blocks the request.

Example of a CORS Error

You might see an error in the browser console.

Access to fetch at ‘http://api.example.com/users’ from origin ‘http://localhost:4200’ has been blocked by CORS policy.

Note: This means the server did not allow your Angular application to access the API.

Why CORS Error Happens in Angular

There are many reasons why CORS errors happen in Angular

1. API Server Does Not Allow Your Origin

The server must allow requests from your frontend domain.

Example allowed origin:

Access-Control-Allow-Origin: http://localhost:4200

Note: If this header is missing, the browser blocks the request.

2. Backend CORS Configuration Missing

If the backend is not configured for CORS, Angular cannot call the API.

Example backend frameworks that require CORS setup:

  1. Node.js
  2. Spring Boot
  3. .NET
  4. Django

3. Incorrect HTTP Headers

Sometimes APIs require additional headers like:

Access-Control-Allow-Headers Access-Control-Allow-Methods

Note: If we did not use then request may fail.

How to Fix CORS Error in Angular?

There are many ways to fix CORS errors in Angular

1. Fix CORS on the Backend

Suppose you are using Node.js as a backend


const cors = require("cors");
app.use(cors());

2. Allow Specific Origin

Example:


Access-Control-Allow-Origin: http://localhost:4200

Note: This allows only your Angular app to access the API.

3. Use Angular Proxy

Angular provides a proxy configuration to avoid CORS errors during development.

Firstly create proxy.conf.json


{
  "/api": {
    "target": "http://localhost:3000",
    "secure": false,
    "changeOrigin": true
  }
}

Now, update angular.json:


ng serve --proxy-config proxy.conf.json

Note: Now your API calls will work without CORS issues.

Angular Proxy vs Backend CORS

Feature Angular Proxy Backend CORS
Usage Development Production
Configuration Angular config Server configuration
Security Not secure Secure
Best Practice Temporary fix Recommended solution

Conclusion

The CORS Error in Angular is usually the result of browser security restrictions combined with missing or incorrect server-side CORS configuration.

Since Angular cannot bypass these browser policies on its own, the correct solution is to configure the API server to send the appropriate CORS headers or use an Angular proxy during local development.

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