Access Control Allow Origin issue in Angular 2

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I have a problem with getting data from my node.js server.

The client side is:

    public getTestLines() : Observable<TestLine[]> {
    let headers = new Headers({ 'Access-Control-Allow-Origin': '*' });
    let options = new RequestOptions({ headers: headers });

    return this.http.get('http://localhost:3003/get_testlines', options)
                .map((res:Response) => res.json())
                .catch((error:any) => Observable.throw(error.json().error || 'Server error')); 
}

in server side I also set the headers:

resp.setHeader('Access-Control-Allow-Origin','*') 
resp.send(JSON.stringify(results))

But I get an error

"XMLHttpRequest cannot load http://localhost:3003/get_testlines. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access."

How can I fix it? When I remove headers it says that this header is required.

Access-Control-Allow-Origin is a response header, not a request header.

You need to have it appear on the response, not the request.

You have attempted to put it on the response:

resp.setHeader('Access-Control-Allow-Origin','*') 

… but it hasn't worked.

This is probably because you haven't put it on the response to the right request. The error message says:

Response to preflight request doesn't pass access control check

You have done something to make the request preflighted. This means that before the browser makes the GET request you are trying to make, it is making an OPTIONS request.

This is, presumably, being handled by a different piece of code on your server so the line resp.setHeader('Access-Control-Allow-Origin','*') isn't being hit.

One thing that causes a preflighted request to be made is the addition of request headers (other than a small number of exceptions). Adding Access-Control-Allow-Origin to the request will trigger a preflighted request, so the first thing to do to try to fix the problem is to remove Access-Control-Allow-Origin from the request.

If that fails, then you need to set up your server so it can respond to the OPTIONS request as well as the GET request.

No 'Access-Control-Allow-Origin' header in Angular 2 app, This a problem with the CORS configuration on the server. It is not clear what server are you using, but if you are using Node+express you can  If you have access to the server, enable CROS requests by adding Access-Control-Allow-Origin: * header.After that, configure cors entry, under system.webServer in web.config file, as in the example below.

Access-Control-Allow-Origin is a response header, not a request header you need to fix the permission in your backend. so you must create cors.js file that contains all necessary permissions.

function crosPermission(){
  this.permission=function(req,res,next){
    res.header('Access-Control-Allow-Origin','*');
    res.header('Access-Control-Allow-Headers','Content-Type');
    res.header('Access-Control-Allow-Methods','GET','POST','PUT','DELETE','OPTIONS');
    next();
  }
}

module.exports= new crosPermission();

next step You need to add some line in your app.js

    var cors=require('./cors');
    app.use(cors.permission)

Access-Control-Allow-Origin: Dealing with CORS Errors in Angular, Fixes for Same Origin problems: CORS, JSONP, proxy, and browser. No '​Access-Control-Allow-Origin' header is present on the requested resource. in Angular JS using $http it gives me CORS error,Please help me out :(. And this proxy can return the Access-Control-Allow-Origin header if it’s not at the Same Origin as your page. Instead of sending API requests to some remote server, you’ll make requests to your proxy, which will forward them to the remote server. Here are a few proxy options. 3rd choice: JSONP (requires server support)

Don't set Access-Control-Allow-Origin on the request, it is never needed there. You should double-check if the header is present on the response (check it in the developer console). It would be helpful if you shared more of the backend code.

Infamious 'Access-Control-Allow-Origin' Error : Angular2, Same origin means same domain AND port, and since you're using a different port, you are restricted. You can set up Angular CLI to use a proxy to avoid this issue  CORS problem with Ionic and angular 2 "No 'Access-Control-Allow-Origin' header is present on the requested resource" ionic. Sorry I am having the same issue here.

If this is going to be rest API => http://localhost:3003/get_testlines

then use @CrossOrigin(origins = "*") to solve the cross domain issue

what's wrong with the http headers in angular 2 using typescript , Also having this header problem, I receive the error message all the time even though I set the "w.Header().Set("Access-Control-Allow-Origin",  I have a web app written with Angular 9 for the frontend and nodejs for the backend. My Express JS server is using the CORS middleware configured as follows: //.. const corsOptions = {

This has nothing to do with the client. Very simply you can solve this problem by adding Cors to the Configure method. like this:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            InitializeDatabase(app);

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseMiddleware<ExceptionToResultMiddleware>();

            app.UseSwagger();

            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
            });

            app.UseCors(s => s.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader());  ==> This section

            app.UseMvc();
        }

Now Restart your project and check again.

CORS problem with Ionic and angular 2 "No 'Access-Control-Allow , Hello. I have a problem with getting data from an api on ionic 2 app. that's what i get [image] my code to grab the data " import { Injectable } from '@angular/core';  Are you setting the "Access-Control-Allow-Origin" in your back-end? Different port means it's different origin.I know localhost was an exclusion to this rule but most recent version of your browser can change it and start to treat as different origin now. – Alexander Trakhimenok Mar 9 at 13:52

Fixing CORS Issues in Your Front-End Angular 7/8 App with Angular , header('Access-Control-Allow-Origin: *');. In Node.js and Express server, you can use the cors package ( npm i cors --save ) as  I have two separate project, one is WebAPI developed in .net Core 2.2 with Windows Authentication and other is Angular. I am stuck in CORS issue. I was able to handle GET request by using withCredentials: true in GET method option as mentioned below, where httpClient is from import { HttpClient } from '@angular/common/http':

No 'Access-Control-Allow-Origin' header is present on the , Origin 'http://localhost:4200' is therefore not allowed access. The call is made from an Angular application that is running on my development http://restlet.​com/company/blog/2016/09/27/how-to-fix-cors-problems/ JS to tokenize the PAN and the merchant server won't be touching the card information. I'm having a persistent problem (400 Bad Request) using the simple file upload API from an AngularJS app running on localhost. The Box side is configured to use Standard OAuth2.0 User Authentication, I get my bearer token (via another server configured at the Redirect URI) and it's working for ot

Fix CORS errors in Angular (when you have access to API), I am trying to call HCI APIs from development environment(localhost:4200) using Angular 2 (version 4.0.0). getting the below error message: "Cross-Origin  CORS headers are simply HTTP headers that tell a browser to allow a web application running at some origin (domain) to access specific resources from a server at a different origin. Browser security disallow you from making cross-domain requests except if the HTTP response has a Control-Allow-Origin header with a * value or the domain of your

Comments
  • Are you using Crome ?If yes then please enable Access-Control-Allow-Origin . Crome has a plugin for cors . For IE you should not get this error after setting headers
  • This is most likely a server-side issue. Are you sure your response actually sends the headers on the OPTIONS request? You can try postman to check the headers, for example.