Reason: CORS request did not succeed

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Reason

Reason: CORS request did not succeed

What went wrong?

The {{Glossary("HTTP")}}  request which makes use of CORS failed because the HTTP connection failed at either the network or protocol level. The error is not directly related to CORS, but is a fundamental network error of some kind.

In many cases, it is caused by a browser plugin (e.g. an ad blocker or privacy protector) blocking the request.

Other possible causes include:

• Trying to access an https resource that has an invalid certificate will cause this error.
• Trying to access an http resource from a page with an https origin will also cause this error.
• From Firefox 68 to Firefox 84, https pages were not permitted to access http://localhost. This has been changed with Bug 1488740.
• The server did not respond to the actual request (even if it responded to the {{Glossary("Preflight request")}} ). One scenario might be an HTTP service being developed that panicked without returning any data.
• The window is in “Private Browsing” mode (which may have security requirements that could block a CORS request).

See also

• CORS errors
• Glossary: {{Glossary("CORS")}} 
• CORS introduction