SharePoint 2013 Workflow Error +Suspend +terminate+ goes in Activity In progress state+ HTTP InternalServerError + An unhandled exception occurred

Hi,

We have a SharePoint 2013 List level multistate parallel block approver workflow. Suddenly it's started suspending or terminating  may be while assigning task to users. But some workflow complete successfully.

When I trigger workflow parallel block logic should work and need to assign task to respective users. But sometimes its assign task to all users in parallel block and some not and goes into activity in progress state. After particular time duration its shows error messages:

[Note]: Same workflow when I I retry It sometimes it work or sometimes not. I checked workflow logic its fine and I used App step in that workflow.

We checked below few steps to resolve but still no luck:

1. We checked  Workflow logic its fine becoz it was working before 2 month ago.
2. No user migration done still date.
3. Checked user profile service and synchronization service  and all are up & running.
4. Checked faulty user/ those user not assign task  in user information list but all email and contact name properties are mentioned properly.
5. We tried after doing deactivating and activating Workflows can use app permissions feature.
6. Tried after republishing workflow but same issue.
7. Granted full app permission through site settings but no luck

Below are few Workflow Error:

Error Message1:

Resume this workflow

RequestorId: <guid>. Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.ApplicationException: HTTP 500 {"SPRequestGuid":["<guid>"],"request-id":["<guid>"],"X-FRAME-OPTIONS":["SAMEORIGIN"],"SPRequestDuration":["185"],"SPIisLatency":["0"],"MicrosoftSharePointTeamServices":["15.0.0.4481"],"X-Content-Type-Options":["nosniff"],"X-MS-InvokeApp":["1; RequireReadOnly"],"Date":["Wed, 09 Mar 2016 09:13:50 GMT"],"Server":["Microsoft-IIS\/8.0"],"X-Powered-By":["ASP.NET"]} at Microsoft.Activities.Hosting.Runtime.Subroutine.SubroutineChild.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)

Error message 2:

Activity in progress

Retrying last request. Next attempt scheduled in less than one minute. Details of last request: HTTP InternalServerError to https://<SiteName>/_vti_bin/client.svc/web/lists/getbyid(guid'<guid>')/Items(12)?%24select=ID%2CABC Correlation Id: <guid> Instance Id: <guid>Retry now

Error Message 3:

Activity in progress

Retrying last request. Next attempt scheduled in less than one minute. Details of last request: HTTP InternalServerError to https://<sitename>/_vti_bin/client.svc/Web/SiteUserInfoList/Items?%24filter=Id+eq+883&%24select=Name Correlation Id: <guid> Instance Id: <guid>Retry now

Error Message 4:

Retrying last request. Next attempt scheduled in less than one minute. Details of last request: HTTP InternalServerError to http://<sitename>/_vti_bin/client.svc/sp.utilities.utility.SendEmail

Your helps will be very appreciated.

Thanks/ Siddheshwar Kohale