Why do I get an error -623 when I install Warehouse on Windows ?

The full pop-up error reads : "An error occurred during the move data process : -623".

This error indicates that the installer was not able to overlay an existing file because that file was in use. You were probably trying to install a release of Warehouse in a directory while one or more existing Warehouse executables were still running from that directory.

The existing Warehouse instance should be quiesced before the installation overlays its files. Stop the Warehouse service and any local Warehouse clients, and wait until any and all Warehouse servers have terminated before re-installing.