I just recently upgraded from ArcMap for desktop 10.4 Basic to ArcMap for desktop 10.6 Standard. Before I upgraded, I would add my shapefiles and the data frame would match the projection of the shapefile and then I would add in the basemap which would match the same projection as the data frame. Now when I do that and then add in the basemap, I get the geographic coordinate system warning because the basemap is in WGS 1984 and my data is NAD 1983. When I had basic, the basemap would automatically import to match the data frame but now it will not. I'm not entirely too sure how to do a transformation, but I do need the data to be accurately projected. Has anyone else experienced this before or know how to fix it?