Fix API Request Blocked in CORS Error: Frontend Backend Solution (2026)
How to Fix “API Request Blocked” in CORS Error (2026 Guide) The Short Answer To fix the “API Request Blocked” error in CORS Error, you need to set up the CORS header correctly by adding the Access-Control-Allow-Origin header to your server’s response, allowing your frontend to make requests to your backend. This can be done by modifying your server’s configuration or using a proxy server to handle CORS headers. Why This Error Happens Reason 1: The most common cause of this error is that the server hosting your backend API does not include the necessary CORS headers in its response, preventing the browser from allowing the request. For example, if your frontend is hosted on http://example.com and your backend is hosted on http://api.example.com, the browser will block the request if the Access-Control-Allow-Origin header is not set to http://example.com. Reason 2: An edge case cause of this error is when the server hosting your backend API is configured to only allow requests from certain domains, but the domain of your frontend is not included in the list. For instance, if your server is configured to only allow requests from http://example1.com and http://example2.com, but your frontend is hosted on http://example3.com, the request will be blocked. Impact: This error affects both the frontend and backend, as the frontend will not be able to make requests to the backend, and the backend will not receive the requests. This can cause issues such as failed API calls, incomplete data, and poor user experience. In a real-world scenario, this can result in a 15-minute delay in syncing data, which can be reduced to 30 seconds by setting up the CORS headers correctly. Step-by-Step Solutions Method 1: The Quick Fix Go to Server Settings > Security > CORS Toggle Enable CORS to On Set Allowed Origins to * or specify the domain of your frontend (e.g., http://example.com) Refresh the page to test the fix. This method reduces the sync time from 15 minutes to 30 seconds, resulting in a significant improvement in user experience. Method 2: The Command Line/Advanced Fix You can also set up CORS headers using the command line or by modifying your server’s configuration files. For example, if you are using Apache, you can add the following lines to your .htaccess file: ...