We upgraded arcgis server from 10.1 to 10.3.1. We have a web service that is published in UTM NAD83 Zone 17N (26917) and we are using submitted xy coordinates in WGS_1984 (4326) to determine if these points fall within a polygon area of a feature class. Prior to the upgrade points 147 points fell outside of the polygon. Now after the upgrade these points are said to fall within the polygon. Adding the service to an arcgis desktop map giving it the data frame properties the coordinate system of the UTM and adding the point using xy the point falls outside of the polygon. When changing the coordinate system of the data frame to the Geographic Coordinate system the service shifts and the point falls within the polygon. We are error checking this points using the query of the service in the rest interface and it says that the point falls in the polygon, this did not happen before using 10.1, as it was saying the points were out of the polygon. Does anyone know of a change in the server to cause this problem? I am aware there can be a +/- 1 meter shift in transforming a NAD 1983 to WGS 1984 datums, just don't understand why it didn't do it before till now.