In a customer, we have QV Server 11.00 deployed, which I did not installed. Is it safe to update (upgrade) from 11.00 to 11.20, by just executing the downloaded exe file? (Licenses are all fine with the customer). I would appreciate for your feedback.
It might not be the answer your looking for but it depends what you define as 'safe'?
V11 to 11.20 are reasonably close versions so there shouldn't be any major problems upgrading, but you should always make a backup of your CAL / licence allocations and reload schedules just incase, also a backup of the server would be a good idea.
You can also review the release notes for the version of 11.2 you are planning to upgrade to, incase you see anything that might effect your documents.
It also depends if this server is a live production server or a dev server, and if you can have the server down for longer than you expect if anything went wrong.
Maybe even request a trial licence from Qlik to mirror your current server, and install a 'test' server with the new version to make sure all your documents function as you'd expect.