Getting parse error on "query" mutation

I am using the following mutation query in my .net application.

{“query”:“mutation orderEditBegin($id: ID!) { orderEditBegin(id: $id) { calculatedOrder { id originalOrder{ id lineItems(first:100){ edges{ node{ id sku } } } } lineItems(first:100){ edges{ node{ id sku } } } } userErrors { field message } }}”,“variables”: {“id”:“gid://shopify/Order/xxxxxxx”}}

while executing I am getting the folowing error message.

{“errors”:[{“message”:“Parse error on "query" (STRING) at [1, 2]”,“locations”:[{“line”:1,“column”:2}]}]}

Make sure you have your Content-Type set to application/json and NOT application/graphql.

If set to graphql, the api expects ONLY the query part of the request.