I have SQL Server 2016 RTM installed and would like to update it to SP1. When I run an SP1 cumulative update, it fails because there is nothing to update. Presumably this is because it needs SP1 to be installed first. When I run the SP1 installer, it wants to create a new instance.
How can I update an existing instance from RTM to SP1 without having to uninstall and reinstall the instance?