Errors: CORSMissingAllowHeaderFromPreflight

Reason

Reason: missing token ‘xyz’ in CORS header ‘Access-Control-Allow-Headers’ from CORS preflight channel

What went wrong?

The Access-Control-Allow-Headers header is sent by the server to let the client know which headers it supports for CORS requests. The value of Access-Control-Allow-Headers should be a comma-delineated list of header names, such as "X-Custom-Information" or any of the standard but non-basic header names (which are always allowed).

If the user agent can't detect any value specified for this header—even though the header is included in the response—this error occurs.

See also

• CORS errors
• Glossary: CORS
• CORS introduction
• HTTP headers