Internal Server Error while using MS Graph Site API with C#

Question

I'm trying to search file on SharePoint using Graph API. Getting the correct result on Microsoft graph-explorer but when I try with C# Getting error Status Code: 500 Reason Phrase:Internal Server Error

Response Details as below:

{
"error": {
 "code": "System.NullReferenceException",
 "message": "Object reference not set to an instance of an object.",
 "innerError": {
  "date": "2021-03-19T16:16:28",
  "request-id": "f3092cda-b813-4507-928e-7e2de84fc88f",
  "client-request-id": "f3092cda-b813-4507-928e-7e2de84fc88f"
  }
 }
}

C# Code I'm using

var searchTerm = "164377_07323_03122021_112659_TaxApp";
var headerStr = @"{{""requests"": [{{""entityTypes"": [""listItem""],""query"": {{""queryString"": ""{0}""}}}}]}}";
headerStr = string.Format(headerStr, searchTerm);
var headerJson = JsonConvert.SerializeObject(headerStr);
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", authResponse.AccessToken);
var content = new StringContent(headerJson, Encoding.UTF8, "application/json");
HttpResponseMessage response = httpClient.PostAsync("https://graph.microsoft.com/v1.0/search/query", content).Result;
var postResult = response.Content.ReadAsStringAsync().Result;

Any pointers where I'm going wrong?

Answer 1

Try using the below code. Looks like your code is getting serialized twice. So I just removed the serialization step and it worked.

var searchTerm = "164377_07323_03122021_112659_TaxApp";
var headerStr = @"{{""requests"": [{{""entityTypes"": [""listItem""],""query"": {{""queryString"": ""{0}""}}}}]}}";
headerStr = string.Format(headerStr, searchTerm);
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", authResponse.AccessToken);
var content = new StringContent(headerStr, Encoding.UTF8, "application/json");
HttpResponseMessage response = httpClient.PostAsync("https://graph.microsoft.com/v1.0/search/query", content).Result;
var postResult = response.Content.ReadAsStringAsync().Result;

You can always test the API requests using fiddler.