Important thing to note:
1. Task is approved and status is showing as completed. But workflow internal status is suspended
2. Recently due to site workflow error team has activated "WorkFlows" feature and reactivated "Workflows can use app permissions feature" in order to resolve this error.
Error Details:
RequestorId: aec66f61-ce53-8997-0000-000000000000. Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.ApplicationException: HTTP 403 {"error":{"code":"-2147024891, System.UnauthorizedAccessException","message":{"lang":"en-US","value":"Access denied. You do not have permission to perform this action or access this resource."}}} {"Transfer-Encoding":g"chunked"],"X-SharePointHealthScore":e"2"],"X-MSDAVEXT_Error":r"917656; Access+denied.+Before+opening+files+in+this+location%2c+you+must+first+browse+to+the+web+site+and+select+the+option+to+login+automatically."],"DATASERVICEVERSION":N"3.0"],"SPRequestGuid":d"aec66f61-ce53-8997-afc9-afc8ba90318f"],"request-id":d"aec66f61-ce53-8997-afc9-afc8ba90318f"],"MS-CV":V"YW/GrlPOl4mvya/IupAxjw.0"],"Strict-Transport-Security":y"max-age=31536000"],"X-FRAME-OPTIONS":S"SAMEORIGIN"],"MicrosoftSharePointTeamServices":s"16.0.0.20029"],"X-Content-Type-Options":s"nosniff"],"X-MS-InvokeApp":p"1; RequireReadOnly"],"Cache-Control":l"max-age=0, private"],"Date":e"Fri, 08 May 2020 08:32:28 GMT"],"P3P":P"CP=""ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR SAMo CNT COM INT NAV ONL PHY PRE PUR UNI"""],"Server":r"Microsoft-IIS/10.0"],"X-AspNet-Version":n"4.0.30319"],"X-Powered-By":y"ASP.NET"]} at System.Activities.Statements.Throw.Execute(CodeActivityContext context) at System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager) at System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation) Exception from activity Throw If Sequence Sequence TryCatch Sequence Microsoft.SharePoint.WorkflowServices.Activities.RetryForDurationPolicy HTTPPost_ReadFieldProperties Sequence DynamicActivity<Int32> If Sequence If If Sequence NintexActivities.WorkflowXaml_a002d968_0889_4d8c_b705_00c13e50ffcd Sequence PickBranch Pick If If Sequence While Wait for Task Sequence SingleTask_CreateListItemCancellationScope Sequence Microsoft.SharePoint.WorkflowServices.Activities.OperatingWebContextScope NintexActivities.WorkflowXaml_f6a19ad8_fae9_46e2_88bb_539a99b9e906 Scan Task Sequence If If If If While State Machine Sequence Flowchart Addendum Request.WorkflowXaml_e24751f7_2d8b_4a6f_8c2c_5cf93fba36ab