I have an issue with #react-oauth/google npm package.
When I using react app on port 3000 and backend django on port 8000 every thing work's, but after I build react app and using port 8000, I try to log in via google, I get that Erros:
Failed to load resource: the server responded with a status of 400 m=credential_button_library:45 [GSI_LOGGER]: The given origin is not allowed for the given client ID.
I did double check on 'Authorised JavaScript origins' and 'Authorised redirect URIs' (image attached)
but the giving origin are allowed, so whats can be the problem?
I read about similar problems here on the site and also tried CHAT GPT but nothing helped.
This is my configurations:
CORS_ALLOWED_ORIGINS = [
"http://localhost:8000",
"http://localhost:3000",
"http://127.0.0.1:3000",
"http://127.0.0.1:8000"
]
class GoogleLogin(SocialLoginView):
adapter_class = GoogleOAuth2Adapter
callback_url = ['http://localhost:8000', 'http://localhost:3000', 'http://127.0.0.1:8000', 'http://localhost:8000/accounts/google/login/callback/'] # !
client_class = OAuth2Client
Comment the CORS_ALLOWED_ORIGINS and try with CORS_ALLOW_ALL_ORIGINS = True and if this doesn't work try to remove this http://localhost:3000 and http://127.0.0.1:8000 from both ( CORS_ALLOWED_ORIGINS and GoogleLogin ) and If the above things doesn't work then try to run your react app on PORT - 3000 and on the URL just change your port to 8000 and then try.
Mod note: This question is about why XMLHttpRequest/fetch/etc. on the browser are subject to the Same Access Policy restrictions (you get errors mentioning CORB or CORS) while Postman is not. This question is not about how to fix a "No 'Access-Control-Allow-Origin'..." error. It's about why they happen.
Please stop posting:
CORS configurations for every language/framework under the sun. Instead find your relevant language/framework's question.
3rd party services that allow a request to circumvent CORS
Command line options for turning off CORS for various browsers
I am trying to do authorization using JavaScript by connecting to the RESTful API built-in Flask. However, when I make the request, I get the following error:
XMLHttpRequest cannot load http://myApiUrl/login.
No 'Access-Control-Allow-Origin' header is present on the requested resource.
Origin 'null' is therefore not allowed access.
I know that the API or remote resource must set the header, but why did it work when I made the request via the Chrome extension Postman?
This is the request code:
$.ajax({
type: 'POST',
dataType: 'text',
url: api,
username: 'user',
password: 'pass',
crossDomain: true,
xhrFields: {
withCredentials: true,
},
})
.done(function (data) {
console.log('done');
})
.fail(function (xhr, textStatus, errorThrown) {
alert(xhr.responseText);
alert(textStatus);
});
If I understood it right you are doing an XMLHttpRequest to a different domain than your page is on. So the browser is blocking it as it usually allows a request in the same origin for security reasons. You need to do something different when you want to do a cross-domain request.
When you are using Postman they are not restricted by this policy. Quoted from Cross-Origin XMLHttpRequest:
Regular web pages can use the XMLHttpRequest object to send and receive data from remote servers, but they're limited by the same origin policy. Extensions aren't so limited. An extension can talk to remote servers outside of its origin, as long as it first requests cross-origin permissions.
WARNING: Using Access-Control-Allow-Origin: * can make your API/website vulnerable to cross-site request forgery (CSRF) attacks. Make certain you understand the risks before using this code.
It's very simple to solve if you are using PHP. Just add the following script in the beginning of your PHP page which handles the request:
<?php header('Access-Control-Allow-Origin: *'); ?>
If you are using Node-red you have to allow CORS in the node-red/settings.js file by un-commenting the following lines:
// The following property can be used to configure cross-origin resource sharing
// in the HTTP nodes.
// See https://github.com/troygoode/node-cors#configuration-options for
// details on its contents. The following is a basic permissive set of options:
httpNodeCors: {
origin: "*",
methods: "GET,PUT,POST,DELETE"
},
If you are using Flask same as the question; you have first to install flask-cors
pip install -U flask-cors
Then include the Flask cors package in your application.
from flask_cors import CORS
A simple application will look like:
from flask import Flask
from flask_cors import CORS
app = Flask(__name__)
CORS(app)
#app.route("/")
def helloWorld():
return "Hello, cross-origin-world!"
For more details, you can check the Flask documentation.
Because
$.ajax({type: "POST" - calls OPTIONS
$.post( - calls POST
Both are different. Postman calls "POST" properly, but when we call it, it will be "OPTIONS".
For C# web services - Web API
Please add the following code in your web.config file under the <system.webServer> tag. This will work:
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="*" />
</customHeaders>
</httpProtocol>
Please make sure you are not doing any mistake in the Ajax call.
jQuery
$.ajax({
url: 'http://mysite.microsoft.sample.xyz.com/api/mycall',
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
type: "POST", /* or type:"GET" or type:"PUT" */
dataType: "json",
data: {
},
success: function (result) {
console.log(result);
},
error: function () {
console.log("error");
}
});
Note: If you are looking for downloading content from a third-party website then this will not help you. You can try the following code, but not JavaScript.
System.Net.WebClient wc = new System.Net.WebClient();
string str = wc.DownloadString("http://mysite.microsoft.sample.xyz.com/api/mycall");
Deep
In the below investigation as API, I use http://example.com instead of http://myApiUrl/login from your question, because this first one working. I assume that your page is on http://my-site.local:8088.
NOTE: The API and your page have different domains!
The reason why you see different results is that Postman:
set header Host=example.com (your API)
NOT set header Origin
Postman actually not use your website url at all (you only type your API address into Postman) - he only send request to API, so he assume that website has same address as API (browser not assume this)
This is similar to browsers' way of sending requests when the site and API has the same domain (browsers also set the header item Referer=http://my-site.local:8088, however I don't see it in Postman). When Origin header is not set, usually servers allow such requests by default.
This is the standard way how Postman sends requests. But a browser sends requests differently when your site and API have different domains, and then CORS occurs and the browser automatically:
sets header Host=example.com (yours as API)
sets header Origin=http://my-site.local:8088 (your site)
(The header Referer has the same value as Origin). And now in Chrome's Console & Networks tab you will see:
When you have Host != Origin this is CORS, and when the server detects such a request, it usually blocks it by default.
Origin=null is set when you open HTML content from a local directory, and it sends a request. The same situation is when you send a request inside an <iframe>, like in the below snippet (but here the Host header is not set at all) - in general, everywhere the HTML specification says opaque origin, you can translate that to Origin=null. More information about this you can find here.
fetch('http://example.com/api', {method: 'POST'});
Look on chrome-console > network tab
If you do not use a simple CORS request, usually the browser automatically also sends an OPTIONS request before sending the main request - more information is here. The snippet below shows it:
fetch('http://example.com/api', {
method: 'POST',
headers: { 'Content-Type': 'application/json'}
});
Look in chrome-console -> network tab to 'api' request.
This is the OPTIONS request (the server does not allow sending a POST request)
You can change the configuration of your server to allow CORS requests.
Here is an example configuration which turns on CORS on nginx (nginx.conf file) - be very careful with setting always/"$http_origin" for nginx and "*" for Apache - this will unblock CORS from any domain (in production instead of stars use your concrete page adres which consume your api)
location ~ ^/index\.php(/|$) {
...
add_header 'Access-Control-Allow-Origin' "$http_origin" always;
add_header 'Access-Control-Allow-Credentials' 'true' always;
if ($request_method = OPTIONS) {
add_header 'Access-Control-Allow-Origin' "$http_origin"; # DO NOT remove THIS LINES (doubled with outside 'if' above)
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Max-Age' 1728000; # cache preflight value for 20 days
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
add_header 'Access-Control-Allow-Headers' 'My-First-Header,My-Second-Header,Authorization,Content-Type,Accept,Origin';
add_header 'Content-Length' 0;
add_header 'Content-Type' 'text/plain charset=UTF-8';
return 204;
}
}
Here is an example configuration which turns on CORS on Apache (.htaccess file)
# ------------------------------------------------------------------------------
# | Cross-domain Ajax requests |
# ------------------------------------------------------------------------------
# Enable cross-origin Ajax requests.
# http://code.google.com/p/html5security/wiki/CrossOriginRequestSecurity
# http://enable-cors.org/
# <IfModule mod_headers.c>
# Header set Access-Control-Allow-Origin "*"
# </IfModule>
# Header set Header set Access-Control-Allow-Origin "*"
# Header always set Access-Control-Allow-Credentials "true"
Access-Control-Allow-Origin "http://your-page.com:80"
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Allow-Headers "My-First-Header,My-Second-Header,Authorization, content-type, csrf-token"
Applying a CORS restriction is a security feature defined by a server and implemented by a browser.
The browser looks at the CORS policy of the server and respects it.
However, the Postman tool does not bother about the CORS policy of the server.
That is why the CORS error appears in the browser, but not in Postman.
The error you get is due to the CORS standard, which sets some restrictions on how JavaScript can perform ajax requests.
The CORS standard is a client-side standard, implemented in the browser. So it is the browser which prevent the call from completing and generates the error message - not the server.
Postman does not implement the CORS restrictions, which is why you don't see the same error when making the same call from Postman.
Why doesn't Postman implement CORS? CORS defines the restrictions relative to the origin (URL domain) of the page which initiates the request. But in Postman the requests doesn't originate from a page with an URL so CORS does not apply.
Solution & Issue Origins
You are making a XMLHttpRequest to different domains, example:
Domain one: some-domain.com
Domain Two: some-different-domain.com
This difference in domain names triggers CORS (Cross-Origin Resource Sharing) policy called SOP (Same-Origin Policy) that enforces the use of same domains (hence Origin) in Ajax, XMLHttpRequest and other HTTP requests.
Why did it work when I made the request via the Chrome extension
Postman?
A client (most Browsers and Development Tools) has a choice to enforce the Same-Origin Policy.
Most browsers enforce the policy of Same-Origin Policy to prevent issues related to CSRF (Cross-Site Request Forgery) attack.
Postman as a development tool chooses not to enforce SOP while some browsers enforce, this is why you can send requests via Postman that you cannot send with XMLHttpRequest via JS using the browser.
For browser testing purposes:
Windows - Run:
chrome.exe --user-data-dir="C://Chrome dev session" --disable-web-security
The command above will disable chrome web security. So for example if you work on a local project and encounter CORS policy issue when trying to make a request, you can skip this type of error with the above command. Basically it will open a new chrome session.
You might also get this error if your gateway timeout is too short and the resource you are accessing takes longer to process than the timeout. This may be the case for complex database queries etc. Thus, the above error code can be disguishing this problem. Just check if the error code is 504 instead of 404 as in Kamil's answer or something else. If it is 504, then increasing the gateway timeout might fix the problem.
In my case the CORS error could be removed by disabling the same origin policy (CORS) in the Internet Explorer browser, see How to disable same origin policy Internet Explorer. After doing this, it was a pure 504 error in the log.
To resolve this issue, write this line of code in your doGet() or doPost() function whichever you are using in backend
response.setHeader("Access-Control-Allow-Origin", "*");
Instead of "*" you can type in the website or API URL endpoint which is accessing the website else it will be public.
Your IP address is not whitelisted, so you are getting this error.
Ask the backend staff to whitelist your IP address for the service you are accessing.
Access-Control-Allow-Headers
For me I got this issue for different reason, the remote domain was added to origins the deployed app works perfectly except one end point I got this issue:
Origin https://mai-frontend.vercel.app is not allowed by Access-Control-Allow-Origin. Status code: 500
and
Fetch API cannot load https://sciigo.herokuapp.com/recommendations/recommendationsByUser/8f1bb29e-8ce6-4df2-b138-ffe53650dbab due to access control checks.
I discovered that my Heroku database table does not contains all the columns of my local table after updating Heroku database table everything worked well.
It works for me by applying this middleware in globally:
<?php
namespace App\Http\Middleware;
use Closure;
class Cors {
public function handle($request, Closure $next) {
return $next($request)
->header('Access-Control-Allow-Origin', '*')
->header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS')
->header('Access-Control-Allow-Headers', "Accept,authorization,Authorization, Content-Type");
}
}
How do I get both https://example.com and https://www.example.com for endpoints to connect?
socket.io connect no problem at htttps://example.com
but not https://www.example.com
my server looks like
const server = http.createServer(app);
const io = socketIo(server, {
cors: {
origin: "https://www.example.com:3000",
methods: ["GET", "POST"],
allowedHeaders: ["my-custom-header"],
credentials: true
}});
and my client endpoint looks like this
const ENDPOINT = 'https://example.com/';
Configure your DNS to point both example.com and www.example.com to the same host IP address and then support both domains with your cors configuration. Then, either URL will go to the same host.
You can avoid cors entirely if you configure socket.io to start immediately with a webSocket, not with the http polling that it usually starts with. You can do that in the client by adding the transports: ['websocket'] option to the client connect.
And, your custom header was probably blocking CORs and requiring pre-flight permission. CORs has two levels, simple and not-simple. When you add a custom header, you force CORs into the not-simple route where it requires preflight which is probably more than the built-in socketio cors features will handle.
I'm a bit new to react and I am trying to fetch Crypto data from the Nomics API. I read their documentations and used axios for my GET request like so:
fetchChartData(currency, start) {
const data = {
key: "key",
currency: currency,
start: start
}
return axios({
method: "get",
url: API_URL + '/exchange-rates/history',
headers: {
"Access-Control-Allow-Origin": "*",
crossorigin: true
},
data
})
}
For which I get:
Access to XMLHttpRequest at 'https://api.nomics.com/v1/currencies/ticker' from origin
'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present
on the requested resource.
So I decided to use Moesif Origin and CORS changer
Access to XMLHttpRequest at 'https://api.nomics.com/v1/exchange-rates/history' from origin 'http://localhost:3000'
has been blocked by CORS policy: Response to preflight request doesn't pass access control check:
It does not have HTTP ok status.
I don't know why it is being blocked because it says "localhost requests are always allowed to ease development" in the documentation.
[![Nomics docs on CORS][1]][1]
My other attempts of fixing this are adding stuff to the headers and proxy.
My proxy went like this, (never proxy-ed before):
const API_URL = `https://cors-anywhere.herokuapp.com/https://api.nomics.com/v1`
fetchChartData(currency, start) {
const key = "key";
return axios({
method: "get",
url: API_URL +
'/exchange-rates/history?' +
`?key=${key}
¤cy=${currency}
&start=${start}`
})
}
With proxy, however, I just get a 401 (Unauthorized).
[1]: https://i.stack.imgur.com/zIT7L.png
The Problem
The problem is that the domain you're using does not match the domain that the API is expecting for development. A domain is identified for CORS purposes (also known as the Same Origin Policy) based on three parts: protocol, host, and port. Using the following domain: https://example.com, I'll explain these three parts below:
Protocol - http or https depending on if security is enabled on the domain. For our example it would be https.
Host - for the example above this would be example.com.
Port - The default ports are typically: 80 for http and 443 for https. In our example, our port is 443.
It's important to know the information above so that you can identify the problem in your code snippet. The documentation notes that localhost is always supported for development. However, your domain http://localhost:3000 does not match the documentation because the ports are different.
The Fix
You'll need to run your application locally at http://localhost (default port 80) for the API call to succeed and pass the CORS preflight test. I don't see it noted above, but if the documentation requires a secure localhost environment then you'd want to run your application locally at https://localhost (default port 443). In addition, you'd probably have to create a self-signed SSL certificate for this to work properly.
I've been trying for hours to allow an angularjs client (localhost:5000) to access the resources of a python server using flask (localhost:5001), but I keep receiving the same error message "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:5001/api. (Reason: expected 'true' in CORS header 'Access-Control-Allow-Credentials').
So far I've tried to:
Allow CORS via flask_cors using
from flask_cors allow CORS
api = Blueprint('api', __name__)
CORS(api, resources={"/api/*: {"origins": "*"}})
Use angular http-proxy-middleware, both with
server.middleware = proxy('/api', {target: 'http://localhost:5001', changeOrigin:true});
and
server.middleware = proxy('/api', {target: 'http://localhost:5001', changeOrigin:true, onProxyRes: function(proxyRes, req, res){proxyRes.headers['Access-Control-Allow-Origin']='*';}});
The Access-Control-Allow-Origin field in the response header is "http://localhost:5000" and not "http://localhost:5001", which is (if I understand it right), what I need. Any ideas?
I had the same problem and fixed it using the CORS decorator #cross_origin() using the parameter supports_credentials=True (note that you can't use origin='*' and support_credentials=True at the same time)
More infos can be found here