So consider updating the Office Web Apps Server during either non-critical or non-business hours.
If you have only one server in your Office Web Apps Server farm, users won’t be able to use Office Web Apps while you are updating the server.
Use the roadmap as a starting point for articles, downloads, and videos that help you deploy and manage Office Web Apps Server.
Are you looking for help with Office Web Apps on your desktop or mobile device?
While this "update is happening, I am unable to access Office files, such as excel , word etc.
Annoying, inconvenient and a liability, since it stops my productivity and I am self employed.