Help to see this exception，Frequently appear

[microdev]

HttpResponse response = httpClient.Post(Api.InsertAttendanceRecordApi, new { record, RecordImage = reocrdImage }, HttpContentTypes.ApplicationJson);

System.InvalidOperationException: This property cannot be set after writing has started.
at System.Net.HttpWebRequest.set_ContentLength(Int64 value)
at EasyHttp.Http.Abstractions.HttpWebRequestWrapper.set_ContentLength(Int64 value) in C:\BuildAgent\work\f8da234c6955617\src\EasyHttp\Http\Abstractions\HttpWebRequestWrapper.cs:line 38
at EasyHttp.Http.HttpRequest.SetupData() in C:\BuildAgent\work\f8da234c6955617\src\EasyHttp\Http\HttpRequest.cs:line 237
at EasyHttp.Http.HttpRequest.SetupBody() in C:\BuildAgent\work\f8da234c6955617\src\EasyHttp\Http\HttpRequest.cs:line 214
at EasyHttp.Http.HttpRequest.PrepareRequest() in C:\BuildAgent\work\f8da234c6955617\src\EasyHttp\Http\HttpRequest.cs:line 292
at EasyHttp.Http.HttpClient.ProcessRequest(String filename) in C:\BuildAgent\work\f8da234c6955617\src\EasyHttp\Http\HttpClient.cs:line 217
at EasyHttp.Http.HttpClient.Post(String uri, Object data, String contentType, Object query) in C:\BuildAgent\work\f8da234c6955617\src\EasyHttp\Http\HttpClient.cs:line 155