CORS Error in Angular – Quick Fix Guide

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.

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