jQuery XML Error: 'Access-Control-Allow-Origin' Header Missing

In this case, the underlying issue is the same-origin policy, which restricts cross-domain requests for security reasons. When making an AJAX request to a different domain than the HTML page's origin, the browser will trigger a CORS (Cross-Origin Resource Sharing) request.

The specific error message indicates that the target server at http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml has not provided the necessary Access-Control-Allow-Origin header in its response. This header specifies which domains are allowed to access the resource.

To resolve this issue, you will need to ensure that the target server includes the appropriate CORS headers in its responses. This can involve modifying the server-side code to add the necessary headers or using a reverse proxy to mirror the request and add the headers there.

Additionally, here are some key points to keep in mind regarding CORS requests:

• Same-origin requests do not require special headers.
• CORS requests require the server to explicitly allow access from the client's origin through the Access-Control-Allow-Origin header.
• Preflight requests may be sent prior to the actual request to determine if the request will be allowed.
• Cross-domain requests may be subject to additional browser prompts or warnings.

By addressing the necessary header configurations, you can enable cross-domain AJAX requests and resolve the error related to missing CORS headers.