I am trying to access the header \'error-detail\' as you can see in the browser networ
I think you are on the right track. To have access to custom headers, your server needs to set this special Access-Control-Expose-Headers
header, otherwise your browser will only allow access to 6 predefined header values as listed in the Mozilla docs.
In your screenshot such a header is not present in the response. You should have a look at the backend for this cors header to also be present in the response.
This is a CORS Issue. Because this is a cross-origin request, the browser is hiding most ot the headers. The server needs to include a Access-Control-Expose-Headers header in its response.
The Access-Control-Expose-Headers1 response header indicates which headers can be exposed as part of the response by listing their names.
By default, only the 6 simple response headers are exposed:
If you want clients to be able to access other headers, you have to list them using the Access-Control-Expose-Headers
header.
For more information, see MDN HTTP Header -- Access-Control-Expose-Headers