I'm making an API call using Axios in a React Web app. However, I'm getting this error in Chrome: Show XMLHttpRequest cannot load https://example.restdb.io/rest/mock-data. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.{ axios .get("https://example.restdb.io/rest/mock-data", { headers: { "x-apikey": "API_KEY", }, responseType: "json", }) .then((response) => { this.setState({ tableData: response.data }); }); } I have also read several answers on Stack Overflow about the same issue, titled Access-Control-Allow-Origin but still couldn't figure out how to solve this. I don't want to use an extension in Chrome or use a temporary hack to solve this. Please suggest the standard way of solving the above issue. After trying out few answers I have tried with this, headers: { 'x-apikey': '59a7ad19f5a9fa0808f11931', 'Access-Control-Allow-Origin' : '*', 'Access-Control-Allow-Methods':'GET,PUT,POST,DELETE,PATCH,OPTIONS', },Now I get the error as, Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers in preflight response I'll have a go at this complicated subject. What is origin?The origin itself is the name of a host (scheme, hostname, and port) i.g. https://www.google.com or could be a locally opened file file:// etc.. It is where something (i.g. a web page) originated from. When you open your web browser and go to https://www.google.com, the origin of the web page that is displayed to you is https://www.google.com. You can see this in Chrome Dev Tools under Security:  The same applies for if you open a local HTML file via your file explorer (which is not served via a server): What has this got to do with CORS issues?When you open your browser and go to https://website.com, that website will have the origin of https://website.com. This website will most likely only fetch images, icons, js files and do API calls towards https://website.com, basically it is calling the same server as it was served from. It is doing calls to the same origin. If you open your web browser and open a local HTML file and in that html file there is javascript which wants to do a request to google for example, you get the following error: The same-origin policy tells the browser to block cross-origin requests. In this instance origin null is trying to do a request to https://www.google.com (a cross-origin request). The browser will not allow this because of the CORS Policy which is set and that policy is that cross-origin requests is not allowed. Same applies for if my page was served from a server on localhost: Localhost server exampleIf we host our own localhost API server running on localhost:3000 with the following code: const express = require('express') const app = express() app.use(express.static('public')) app.get('/hello', function (req, res) { // res.header("Access-Control-Allow-Origin", "*"); res.send('Hello World'); }) app.listen(3000, () => { console.log('alive'); })And open a HTML file (that does a request to the localhost:3000 server) directory from the file explorer the following error will happen: Since the web page was not served from the localhost server on localhost:3000 and via the file explorer the origin is not the same as the server API origin, hence a cross-origin request is being attempted. The browser is stopping this attempt due to CORS Policy. But if we uncomment the commented line: const express = require('express') const app = express() app.use(express.static('public')) app.get('/hello', function (req, res) { res.header("Access-Control-Allow-Origin", "*"); res.send('Hello World'); }) app.listen(3000, () => { console.log('alive'); })And now try again: It works, because the server which sends the HTTP response included now a header stating that it is ok for cross-origin requests to happen to the server, this means the browser will let it happen, hence no error. How to fix things (One of the following)
Example flowFollowing is taken from: https://web.dev/cross-origin-resource-sharing/#how-does-cors-work Remember, the same-origin policy tells the browser to block cross-origin requests. When you want to get a public resource from a different origin, the resource-providing server needs to tell the browser "This origin where the request is coming from can access my resource". The browser remembers that and allows cross-origin resource sharing.
More linksHere is another good answer, more detailed as to what is happening: https://stackoverflow.com/a/10636765/1137669 If your backend support CORS, you probably need to add to your request this header: headers: {"Access-Control-Allow-Origin": "*"}[Update] Access-Control-Allow-Origin is a response header - so in order to enable CORS - you need to add this header to the response from your server. But for the most cases better solution would be configuring the reverse proxy, so that your server would be able to redirect requests from the frontend to backend, without enabling CORS. You can find documentation about CORS mechanism here: https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS I had the same error. I solved it by installing CORS in my backend using npm i cors. You'll then need to add this to your code: const cors = require('cors'); app.use(cors());This fixed it for me; now I can post my forms using AJAX and without needing to add any customized headers. Using the Access-Control-Allow-Origin header to the request won't help you in that case while this header can only be used on the response... To make it work you should probably add this header to your response.You can also try to add the header crossorigin:true to your request. For Spring Boot - React js apps I added @CrssOrigin annotation on the controller and it works: @CrossOrigin(origins = {"http://localhost:3000"}) @RestController @RequestMapping("/api")But take care to add localhost correct => 'http://localhost:3000', not with '/' at the end => 'http://localhost:3000/', this was my problem. First of all, CORS is definitely a server-side problem and not client-side but I was more than sure that server code was correct in my case since other apps were working using the same server on different domains. The solution for this described in more details in other answers. My problem started when I started using axios with my custom instance. In my case, it was a very specific problem when we use a baseURL in axios instance and then try to make GET or POST calls from anywhere, axios adds a slash / between baseURL and request URL. This makes sense too, but it was the hidden problem. My Laravel server was redirecting to remove the trailing slash which was causing this problem. In general, the pre-flight OPTIONS request doesn't like redirects. If your server is redirecting with 301 status code, it might be cached at different levels. So, definitely check for that and avoid it. I had a similar problem when I tried to create the React Axios instance. I resolved it using the below approach. const instance = axios.create({ baseURL: "https://jsonplaceholder.typicode.com/", withCredentials: false, headers: { 'Access-Control-Allow-Origin' : '*', 'Access-Control-Allow-Methods':'GET,PUT,POST,DELETE,PATCH,OPTIONS', } });npm i cors const app = require('express')() app.use(cors()) Above code worked for me. I imagine everyone knows what cors is and what it is for. In a simple way and for example if you use nodejs and express for the management, enable it is like this Dependency: https://www.npmjs.com/package/cors app.use ( cors ({ origin: "*", ... more }) );And for the problem of browser requests locally, it is only to install this extension of google chrome. Name: Allow CORS: Access-Control-Allow-Origin https://chrome.google.com/webstore/detail/allow-cors-access-control/lhobafahddgcelffkeicbaginigeejlf?hl=esThis allows you to enable and disable cros in local, and problem solved. After a long time of trying to figure out how CORS works. I tried many way to fix it in my FE and BE code. Some ways CORS errors appearance, some ways the server didn't receive body from client, and other errors... And finally got this way. I'm hoping this can help someone: BE code (NodeJS + Express) var express = require("express"); const cors = require("cors"); var app = express(); app.use( cors({ origin: "*", }) ); app.use(function (req, res, next) { res.header("Access-Control-Allow-Origin", "*"); next(); }); // your routers and codesMy FE code (JS): fetch(url, { method: 'POST', headers: { 'Content-Type': 'application/json', Connection: 'Keep-Alive', Authorization: `Bearer test`, }, body: JSON.stringify(data), });As I understand the problem is that request is sent from localhost:3000 to localhost:8080 and browser rejects such requests as CORS. So solution was to create proxy My solution was : import proxy from 'http-proxy-middleware' app.use('/api/**', proxy({ target: "http://localhost:8080" }));$ npm install cors After installing cors from npm add the code below to your node app file. It solved my problem. var express = require('express') var cors = require('cors') var app = express() app.use(cors())0 Vakhtang Elisabedashvili try it proxy package.json add code: "proxy":"https://localhost:port"and restart npm enjoy same code const instance = axios.create({ baseURL: "/api/list", });You can create a new instance of axios with a custom config, and then use this new configured instance, use this exported function like, import axios from '../YOUR_DIRECTORY/axios-configure'; axios.get();// wont throw corsdont import axios from axios; NOTE this solution will work for them who facing CORS at local environment as local starts at 5000 and backend at 8080, but in production, build gets deployed from java 8080 no CORS in productions (Facing CORS at only local environment) In node js(backend), Use cors npm module $ npm install corsThen add these lines to support Access-Control-Allow-Origin, const express = require('express') const app = express() app.use(cors()) app.get('/products/:id', cors(), function (req, res, next) { res.json({msg: 'This is CORS-enabled for a Single Route'}); });You can achieve the same, without requiring any external module app.use(function(req, res, next) { res.header("Access-Control-Allow-Origin", "*"); res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept"); next(); });}, "proxy": "http://localhost:8080", "devDependencies": { use proxy in package.json How do you add AccessSolution. Modify the header. In your get request, add the following to the header in the app.get function: res. header("Access-Control-Allow-Origin", "true"); ... . Installing CORS. You can add the following code to your code to solve the issue: const cors = require('cors'); app. ... . Using Express.. How do you set no CORS in Axios?axios add no cors. Axios({. method: 'post',. headers: { 'Content-Type': 'application/x-www-form-urlencoded' },. url: 'https://localhost:44346/Order/Order/GiveOrder',. data: order.. }). then(function (response) {. console. log(response. data);. How do I fix CORS header AccessIf the server is under your control, add the origin of the requesting site to the set of domains permitted access by adding it to the Access-Control-Allow-Origin header's value. You can also configure a site to allow any site to access it by using the * wildcard. You should only use this for public APIs.
Has been blocked by CORS policy no Access[Solved] Axios request has been blocked by cors no 'Access-Control-Allow-Origin' header is present on the requested resource. Solution 1: Access-Control-Allow-Origin is a response header - so in order to enable CORS - We need to add this header to the response from server.
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No access-control-allow-origin header is present on the requested resource. react axios
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