Common reasons for the error
CORS (Cross-Origin Resource Sharing) Issues
You may run into CORS issues if you are trying to request a different domain than the one your site is hosted on.
The server you request must include the appropriate CORS headers in its response; otherwise, browsers will block the request for security reasons.
The server might be down, or other network-related issues could prevent the fetch request from completing.
Request Method Issues
The server might not support the HTTP method you’re using in your fetch request.
Headers and Credentials
There might be issues with the headers you are sending, or you might need to include credentials with your request.
Ensure that the browser you are testing supports the Fetch API.
HTTPS vs HTTP
If you are trying to make requests from an HTTPS site to an HTTP endpoint, browsers might block it due to mixed content restrictions.
How to fix the error?
Here are the steps to fix the error.
- If it’s a CORS issue, you may need to adjust the server’s response headers or use a proxy to bypass CORS for development purposes.
- Verify the URL and ensure it’s correct.
- If using service workers, ensure they are correctly set up and not causing the issue.
- Check your fetch request setup (method, headers, etc.) and ensure everything is correctly configured.
Debugging is a process of elimination. By systematically ruling out potential causes, you can narrow down the issue and find a solution.