I have seen this problem quite a few times and it pops up time and again. This is a CORS(i.e. Cross origin request issue).The exact error I got this time is as follows:
XMLHttpRequest cannot load
https://myURL/myappdomain.subdomain.qual1/$count. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 401.
Following are the possible solutions I have worked out in past. But they dont always work. They are URL specific solutions:
1) Having CORS plugin on chrome installed
2) Disabling web security from command line "--disable-web-security"
3) using 'jsonp' as format instead of 'json'
4) toggling cross-origin to "true" or "false".
Questions I need answer for
1) Why do we get this error? Is it something that the Server is imposing on the client pages?
2) What is the safest way to solve this? i.e. The method in which there is not security vulnerability and a reliable method.
3) Why cors is never an issue for API calls made from within nodeJS code?
Related
I have been trying to use a web API in javascript but I repeatedly keep getting this error:
Access to fetch at
'https://eodhistoricaldata.com/api/fundamentals/AAPL.US?api_token={token}'
from origin 'http://127.0.0.1:5500' has been blocked by CORS policy:
The 'Access-Control-Allow-Origin' header has a value
'https://eodhistoricaldata.com/*' that is not equal to the supplied
origin. Have the server send the header with a valid value, or, if an
opaque response serves your needs, set the request's mode to 'no-cors'
to fetch the resource with CORS disabled.
How should I resolve this? I installed a plugin to set the desirable header but others can't install the plugin to view data.
Perhaps this is what you meant, but it's the HTTP response from your API at 'https://eodhistoricaldata.com/' that must include the Access-Control-Allow-Origin header in its HTTP responses.
If the value of that header is 'https://eodhistoricaldata.com/*', your web browser will trigger a CORS error if you call that API from code hosted in any domain other than 'https://eodhistoricaldata.com'. To fix this, you need to change the value your API returns for this header to the domain you want to allow to call your API.
Returning the value * for the Access-Control-Allow-Origin header will allow applications from any domain to call your API without a CORS error.
My website is www.yourentacar.co.uk
when I navigate to the website using http
http://www.yourentacar.co.uk
write any letters in the search box
AJAX returns results.
The problem occurs when I navigate to the website using https
https://www.yourentacar.co.uk
write any letters in the search box
the page is frozen and I do not get any result.
I have been trying to solve this problem for several days but I can't find a solution.
Such a problem is normally due to CORS issue, where a page on HTTP is not allowed to make a request to HTTPS unless allowed specifically via 'Access-Control-Allow-Origin' header.
If you open console, you might see an error like this
XMLHttpRequest cannot load [your api including protocol]. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin [your domain including protocol] is therefore not allowed access.
You can fix this a few ways.
Make your site always run on https
Set Access-Control-Allow-Origin on your ajax call to allow non ssl domain to visit it, in your case.. something like header Access-Control-Allow-Origin: http://www.yourentacar.co.uk
I'm getting an a "XMLHttpRequest cannot load https://example.com. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8000' is therefore not allowed access."
This is my componenDidMount(), and I'm using axios to get the data from my API.
componentDidMount() {
this.serverRequest = axios.get(this.props.source).then(event =>{
this.setState({
title: event.data[0].name
});
});
}
I'm using "python -m SimpleHTTPServer" on the terminal, to run 'http://localhost:8000'.
I'm using the Chrome browser, and if I turn on the Chrome CORS plugin (to enable cross origin resource sharing), the app works, and I see data displayed from the API on the DOM. But I know that using the CORS plugin is bad, so how should I fix the 'Access-Control-Allow-Origin' error officially?
With Axios, can I somehow add dataType: "jsonp", if that would fix it?
This is a restriction made by the browser for security reasons when you try to access content in some domain from another domain. You overcome this, you need to set the following in your header
Access-Control-Request-Method
Access-Control-Request-Headers
Many sites restrict CORS. The best way to achieve your goal is to make your python server as a proxy. See the example.
//Request from the client/browser
http://localhost:8000/loadsite?q=https%3A%2F%2Fexample.com
//In your server
1. Handle the request
2. Get the query param(url of the website)
3. Fetch it using your python server
4. Return the fetching data to the client.
This should work.
I am doing a login to connect through a service layer to a Linux server that has sap b1, and I get the following error.
XMLHttpRequest cannot load https://hanab1:50000/b1s/v1/Login. A wildcard '*' cannot be used in the 'Access-Control-Allow-Origin' header when the credentials flag is true. Origin 'null' is therefore not allowed access.
I find from google chrome and despite attempts, always the same error is generated, the funny thing is that when we perform the video https://www.youtube.com/watch?v=ilDH8nhnp4o,I get the error above dimensioned, but when I enter the URL directly the next line https://hanab1:50000/B1S/v1, see I have access to all information.
If anyone can help me in advance I thank you for your collaboration and interest.
In simple words, you cannot. To enable the Access Control, you need to change the way, the server sends you the headers. If your server is a PHP based one:
<?php
header("Access-Control-Allow-Origin: *");
And for SAP (if it uses Apache), the headers should be:
Header set Access-Control-Allow-Origin "*"
You can learn for other servers from here: I want to add CORS support to my server.
I am using CORS POST request with everything taken care as given #http://www.html5rocks.com/en/tutorials/cors/
Server sets Response header to:
'Access-Control-Allow-Origin':'*' and I can see this header value in IE developer tool.
But on IE10 browser I see console message as "SEC7118: XMLHttpRequest for http:// required Cross Origin Resource Sharing (CORS).
When I check on Microsoft site it has below given explanation.
http://msdn.microsoft.com/en-us/ie/dn423949(v=vs.94).aspx
SEC7118
Description:
"XMLHttpRequest for [URL] required Cross Origin Resource Sharing (CORS). "
An XMLHttpRequest was made to a domain that was different than your page's domain. This requires the server to return an "Access-Control-Allow-Origin" header in its response headers, but one was not returned.
Suggested Fix:
The server must support CORS requests and return an appropriate "Access-Control-Allow-Origin" header with the resource. See CORS for XHR in IE10 for more info about CORS in response headers.
Questions:
I want to know if this console message is an ERROR ??
Will this cause any failures ??
Why do I get this message even after setting response header 'Access-Control-Allow-Origin' value to '*'??
Does 'Access-Control-Allow-Origin' value has to be origin name for
IE10 to work? I know * is not a very good option, But does IE
requires exact origin name ??
I kept URL's and cookie details hidden from these images.
From MSDN:
Security error codes are in the form SEC7xxx [In IE]
Pertaining to SEC7118:
An XMLHttpRequest was made to a domain that was different than your page's domain. This requires the server to return an "Access-Control-Allow-Origin" header in its response headers, but one was not returned.
Note This error code was removed in IE11 on Windows 10. It remains in IE11 for Windows 8.1 and Windows 7.
So it is technically viewed as an error from IE's perspective, but certainly isn't one (hence why it is going away). Access-Control-Allow-Origin is set on a resource, but isn't necessarily sent back with the request. If a specified resource DOESN'T have Access-Control-Allow-Origin:* (or a domain), the resource would not be accessible and the server would likely return a 503 or 404 and you would see a true error message in the console similar to the below:
XMLHttpRequest cannot load http://example.com/. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://blog.example.com' is therefore not allowed access.
I encountered SEC7118 when CORS was set up correctly. I verified that the requests were completing with status 200 using the network debugger. So, you can disregard this message if your application is otherwise functioning properly.
I have seen this error in IE11:
SEC7118: XMLHttpRequest for http:// required Cross Origin Resource Sharing (CORS)
Adding the following to my .htaccess fixed it:
<IfModule mod_setenvif.c>
<IfModule mod_headers.c>
<FilesMatch "\.(cur|gif|ico|jpe?g|png|svgz?|webp)$">
SetEnvIf Origin ":" IS_CORS
Header set Access-Control-Allow-Origin "*" env=IS_CORS
</FilesMatch>
</IfModule>
</IfModule>
Reference:
https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image
I had this same issue. It has to do with Internet Explorer's handing of third party cookies. You can fix this issue by going into Tools>Internet Options then selecting the Privacy tab. If you change the setting to "Accept All Cookies" you will no longer see that message.
The safer way to do this would be to click on the "Sites" button and allow cookies from your site's url.