If you send it as JSON type, you have to send a JSON file see this docs https://dgraph.io/docs/graphql/api/requests/
Otherwise, change the type to Content-Type: application/graphql
If you send it as JSON type, you have to send a JSON file see this docs https://dgraph.io/docs/graphql/api/requests/
Otherwise, change the type to Content-Type: application/graphql