I have a high trust app that is working perfectly making Search requests on behalf of logged in users through the REST api, until they use SharePoint as the queryterm.
This throws an HTTP 500 error with the following entry in the ULS logs:-
ResultMapperException caught in SearchService.Execute method. Exception: Microsoft.Office.Server.Search.REST.ResultMapperException: Two relevant result tables with same id.
at Microsoft.Office.Server.Search.REST.ResultMapper.MapRelevantResults(ResultTable table, QueryResult queryResult)
at Microsoft.Office.Server.Search.REST.ResultMapper.Map(ResultTableCollection result)
at Microsoft.Office.Server.Search.REST.SearchService.Execute[T](Action`1 initializer, Func`2 executor)
If you search for SharePoint through the UI it's fine, and if I specify a result source or not, it fails on this querytext.
I've only seen one other instance of this error mentioned on the net, and the queryterm was different, but the result the same.