The server refuses the request because the Content-Type is not supported.
// For JSON:
fetch('/api', {
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify(data),
});
// For form data:
const form = new FormData();
fetch('/api/upload', { body: form }); // Content-Type auto-setMatch Content-Type to the actual body format.
ObserveOne validates Content-Type headers across your API endpoints.
Start Monitoring FreeThe server cannot process the request due to malformed syntax, invalid parameters, or bad encoding.
The request requires authentication. The client must provide valid credentials.
The server understood the request but refuses to authorize it. Authentication won't help — the user lacks permissions.
The server cannot find the requested resource. The URL may be wrong, the resource may have been deleted, or the route doesn't exist.
The HTTP method (GET, POST, PUT, DELETE) is not supported for this endpoint.