I am trying to send a GET request to a server (the server and the local host have the same domain), however I keep getting the following error:
Response to preflight request doesn't pass access control check: No
'Access-Control-Allow-Origin' header is present on the requested
resource.
This is the code I use to send the request
$.ajaxSetup({
headers: {
'Access-Control-Allow-Origin': "*",
'Access-Control-Allow-Methods': "GET, POST, PATCH, PUT, DELETE, OPTIONS",
'Access-Control-Allow-Headers': "Origin, Content-Type, X-Auth-Token"
}
});
$.get(myurl, function(data) {
console.log(data);
});
I not sure how to fix this error, since I'm new to web development.
Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
The Access-Control control headers have to be sent by the responding server. Depending on the response and requesting page, browser may allow the request to proceed, out just show the error you got.
If adding the headers was enough, any CORS policy would be moot: any page could access any resource.
the server and the local host have the same domain
I'm not sure what you mean here, but apparently your page is loaded from a different domain than myurl points to.
The Access-Control headers should be sent by the server, not by the client.
You have to set Access-Control in your server app, If your back-end is on java then you can use filter to set Access-Control headers
I've got a serverless function on Azure, written in Javascript, returning some HTML and front end JS. The JS is supposed to access a blob file hosted remotely. Right now, it's throwing me CORS errors. Even though I've added Access-Control-Allow-Origin to the headers:
headers: {
'Content-Type': 'text/html',
'Access-Control-Allow-Origin': '*'
'Access-Control-Allow-Origin': 'https://tif.azurewebsites.net',
'Access-Control-Allow-Methods': 'GET, POST, OPTIONS, PUT, PATCH, DELETE',
'Access-Control-Allow-Credentials':'true',
'Access-Control-Allow-Headers': 'X-Requested-With,content-type',
'Access-Control-Allow-Headers' : 'Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers'
}
The Content-Type header works perfectly.
What am I doing wrong here?
As discussed in the comments, since your JS code is accessing the Blob Storage you would need to configure CORS settings for Blob Storage. When configuring CORS settings, please make sure that all settings are correct. A slight mismatch in the settings would result in 403 error returned from Storage Service.
Based on your environment, here's what I would recommend:
Allowed Origins: https://tif.azurewebsites.net
Allowed Methods: Select all of the methods.
Allowed Headers: *
Exposed Headers: *
I'm trying to send files to my server with a post request, but when it sends it causes the error:
Request header field Content-Type is not allowed by Access-Control-Allow-Headers.
So I googled the error and added the headers:
$http.post($rootScope.URL, {params: arguments}, {headers: {
"Access-Control-Allow-Origin" : "*",
"Access-Control-Allow-Methods" : "GET,POST,PUT,DELETE,OPTIONS",
"Access-Control-Allow-Headers": "Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With"
}
Then I get the error:
Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers
So I googled that and the only similar question I could find was provided a half answer then closed as off topic. What headers am I supposed to add/remove?
I had the same problem. In the jQuery documentation I found:
For cross-domain requests, setting the content type to anything other than application/x-www-form-urlencoded, multipart/form-data, or text/plain will trigger the browser to send a preflight OPTIONS request to the server.
So though the server allows cross origin request but does not allow Access-Control-Allow-Headers , it will throw errors. By default angular content type is application/json, which is trying to send a OPTION request. Try to overwrite angular default header or allow Access-Control-Allow-Headers in server end. Here is an angular sample:
$http.post(url, data, {
headers : {
'Content-Type' : 'application/x-www-form-urlencoded; charset=UTF-8'
}
});
The server (that the POST request is sent to) needs to include the Access-Control-Allow-Headers header (etc) in its response. Putting them in your request from the client has no effect. You should remove the 'Access-Control-Allow-...' headers from your POST request.
This is because it is up to the server to specify that it accepts cross-origin requests (and that it permits the Content-Type request header, and so on) – the client cannot decide for itself that a given server should allow CORS.
The requestor (web browser) may 'preflight' test what the server's Same Origin Policy is by sending an 'OPTIONS' request (ie not the 'POST' or 'GET' request you intend). If the response to the 'OPTIONS' request contains 'Access-Control-Allow-...' headers that permit the headers, origin, or methods your request is using, then the requester/browser will send your 'POST' or 'GET' request.
(obscure note:) The Access-Control-Allow-... have the value '' rather than listing the specific origin, headers, or methods allowed. However, and old Android WebView client I was using didn't honor the '' wildcard and needed the specific headers listed in the Access-Control-Allow-Headers header in the response to the OPTIONS request.
If that helps anyone, (even if this is kind of poor as we must only allow this for dev purpose) here is a Java solution as I encountered the same issue.
[Edit] Do not use the wild card * as it is a bad solution, use localhost if you really need to have something working locally.
public class SimpleCORSFilter implements Filter {
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
HttpServletResponse response = (HttpServletResponse) res;
response.setHeader("Access-Control-Allow-Origin", "my-authorized-proxy-or-domain");
response.setHeader("Access-Control-Allow-Methods", "POST, GET");
response.setHeader("Access-Control-Max-Age", "3600");
response.setHeader("Access-Control-Allow-Headers", "Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With");
chain.doFilter(req, res);
}
public void init(FilterConfig filterConfig) {}
public void destroy() {}
}
You can activate the proper header in PHP with this:
header('Access-Control-Allow-Origin: *');
header("Access-Control-Allow-Methods: GET, POST, OPTIONS, PUT, DELETE");
header("Access-Control-Allow-Headers: Content-Type, Access-Control-Allow-Headers, X-Requested-With");
The server (that the POST request is sent to) needs to include the Content-Type header in its response.
Here's a list of typical headers to include, including one custom "X_ACCESS_TOKEN" header:
"X-ACCESS_TOKEN", "Access-Control-Allow-Origin", "Authorization", "Origin", "x-requested-with", "Content-Type", "Content-Range", "Content-Disposition", "Content-Description"
That's what your http server guy needs to configure for the web server that you're sending your requests to.
You may also want to ask your server guy to expose the "Content-Length" header.
He'll recognize this as a Cross-Origin Resource Sharing (CORS) request and should understand the implications of making those server configurations.
For details see:
http://www.w3.org/TR/cors/
http://enable-cors.org/
The following works for me with nodejs:
xServer.use(function(req, res, next) {
res.setHeader("Access-Control-Allow-Origin", 'http://localhost:8080');
res.setHeader('Access-Control-Allow-Methods', 'POST,GET,OPTIONS,PUT,DELETE');
res.setHeader('Access-Control-Allow-Headers', 'Content-Type,Accept');
next();
});
If you are using localhost and PHP set to this to solve the issue:
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Headers: Content-Type');
From your front-end use:
{headers: {"Content-Type": "application/json"}}
and boom no more issues from localhost!
In Asp Net Core, to quickly get it working for development; in Startup.cs, Configure method add
app.UseCors(options => options.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader());
The headers you are trying to set are response headers. They have to be provided, in the response, by the server you are making the request to.
They have no place being set on the client. It would be pointless having a means to grant permissions if they could be granted by the site that wanted permission instead of the site that owned the data.
If anyone experiences this problem with an express server, add the following middleware
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
if you testing some javascript requests for ionic2 or angularjs 2 , in your chrome on pc or mac , then be sure that you install CORS plugin for chrome browser to allow cross origin .
mayba get requests will work without needing that , but post and puts and delete will need you to install cors plugin for testing to go without problems , that definitley not cool , but i do not know how people do it without CORS plugin .
and also be sure the json response is not returning 400 by some json status
this is backend problem. if use sails api on backend change cors.js and add your filed here
module.exports.cors = {
allRoutes: true,
origin: '*',
credentials: true,
methods: 'GET, POST, PUT, DELETE, OPTIONS, HEAD',
headers: 'Origin, X-Requested-With, Content-Type, Accept, Engaged-Auth-Token'
};
In my case, I'm receiving several parameters as #HeaderParam into a web service method.
These parameters MUST be declared in your CORS filter that way:
#Provider
public class CORSFilter implements ContainerResponseFilter {
#Override
public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException {
MultivaluedMap<String, Object> headers = responseContext.getHeaders();
headers.add("Access-Control-Allow-Origin", "*");
...
headers.add("Access-Control-Allow-Headers",
/*
* name of the #HeaderParam("name") must be declared here (raw String):
*/
"name", ...);
headers.add("Access-Control-Allow-Credentials", "true");
headers.add("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, HEAD");
}
}
Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers error
means that Access-Control-Allow-Origin field of HTTP header is not handled or allowed by response. Remove Access-Control-Allow-Origin field from the request header.
For me, Added the following to my server's web.config file:
<system.webServer>
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="https://other.domain.com" />
<add name="Access-Control-Allow-Methods" value="GET,POST,OPTIONS,PUT,DELETE" />
<add name="Access-Control-Allow-Headers" value="Content-Type,X-Requested-With" />
</customHeaders>
</httpProtocol>
<system.webServer>
For me I had wildcard "*" Access-Control-Allow-Headers in web.config:
<add name="Access-Control-Allow-Headers" value="*" />
This solution works for most navigators but not for Safari or IE
It turned out the solution was to add manually all the custom header to the web.config:
<system.webServer>
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="https://somedomain.com" />
<add name="Access-Control-Allow-Methods" value="GET,POST,OPTIONS,PUT,DELETE" />
<add name="Access-Control-Allow-Headers" value="custom-header1, custome-header2, custome-header3" />
</customHeaders>
</httpProtocol>
<system.webServer>
I'm using an Express app on Heroku. I try to make a RESTful request to it from another NodeJS app.
Here's a snippet from the Heroku app, called app.js:
var express= require("express");
app.get("/results",function(req,res){
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
res.header("Access-Control-Allow-Methods", "GET,PUT,POST,DELETE,OPTIONS");
});
And here's a snippet from an app I run locally, local-app.js:
var request= require("superagent");
var req= request.get("http://url-to-app-js.com?query=1").set(
"Access-Control-Allow-Origin", "http://url-to-app-js.com",
"Access-Control-Allow-Methods", "GET,PUT,POST,DELETE,OPTIONS",
"Access-Control-Allow-Headers", "Content-Type, Authorization, Content-Length, X-Requested-With"
);
req.end(function(err,res){
// do things
});
When I run local-app.js, I got this error in my browser console: esponse 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.
I know that I could run the browser, Chromium, with certain security settings turned off, but I need to be able to run this without doing so.
What am I doing wrong? How do I fix it?
Access-Control-Allow-Origin, Access-Control-Allow-Methods, and Access-Control-Allow-Headers are response headers. They shouldn't appear in the request at all.
By adding non-standard headers you make the request a preflighted request instead of a simple request. (You might be doing something else that makes it a preflighted request, but the extra headers definitely do not help).
A preflighted request sends a OPTIONS request to find out if it is allowed by CORS before making the request (GET in this case) you actually want to make.
You are only setting the CORS response headers when you receive a GET request. Since you don't respond with them to the OPTIONS request, the browser refuses to make the GET request.
I have an app on Heroku at http://random-name.herokuapp.com that sends emails with Mandrill. However, regardless of whether I'm running the app locally at localhost:5000 or remotely on Heroku, I throw the following error when trying to send emails:
XMLHttpRequest cannot load
https://mandrillapp.com/api/1.0/messages/send.json. Response to
preflight request doesn't pass access control check: A wildcard '*'
cannot be used in the 'Access-Control-Allow-Origin' header when the
credentials flag is true. Origin 'http://random-name.herokuapp.com' is
therefore not allowed access.
There's a lot of documentation on Stack Overflow about this error (see CORS: Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true), and consequently, I set my express headers to the following:
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "http://localhost:5000 http://random-name.herokuapp.com");
res.header('Access-Control-Allow-Credentials', true);
res.header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
However, this doesn't seem to solve the issue. I couldn't find anything useful in Mandrill's documentation either. I'm guessing I'm specifying the headers incorrectly, or perhaps they aren't even being used. Any ideas?
Access-Control-Allow-Origin takes a single value, not a space separated list.
You need to return whatever the client sends in the Origin request header (test to make sure that is an acceptable origin to you first though!).