No, I'm saying about macOS Sierra itself but ESET web protection breaks caching AppStore contents.
macOS Sierra beta5 updater is just one of them, iTunes updater, Xcode, etc.
macOS Sierra client doesn't have ESET.
OSX 10.11.6 server runs Endpoint Antivirus and "Cache" service.
macOS Sierra client fetch updater with AppStore and "Cache" works with it, then corrupts update contents.
It's ESET issue on OSX 10.11.6, IMO.