Here are a few title options, combining question format with the article\'s content: **Focus on the Problem:** * **AJAX Requests Failing: Why \'No \'Access-Control-Allow-Origin\' Header\'?

Debugging Cross-Origin Resource Sharing Issue

When attempting to make an AJAX request, you may encounter the error "No 'Access-Control-Allow-Origin' header is present on the requested resource." This error indicates that the web server hosting the requested resource does not allow cross-origin requests from your origin.

Cause of the Error:

In your case, you are using .htaccess to rewrite URLs and an HTML base tag. This configuration can prevent browsers from sending the appropriate Origin header in AJAX requests, leading to the error.

Solution:

To resolve this issue, you need to configure the web server to allow cross-origin requests. This can be done by adding the following "Access-Control-Allow-Origin" header to the HTTP response:

response.addHeader("Access-Control-Allow-Origin", "*");

Note: The asterisk (*) in the code above allows access to all domains. If you want to restrict access to a specific domain, use the following:

response.addHeader("Access-Control-Allow-Origin", "http://www.example.com");

Additional Information:

• addHeader Method: Use addHeader instead of setHeader, as setHeader overwrites existing headers.
• Browser Support: Not all browsers support the Origin header, so the solution may not work for all clients.
• For More Details: Refer to this blog post for more information on cross-origin resource sharing and the Access-Control-Allow-Origin header: [Blog Post Link]

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