I too was getting the 1603 error message and finally discovered that a previous attempt to install google earth had apparently been successful, but it hadn't told me - so it would seem that, as a previous reply said, Error 1603 means something like, "You stupid nit!
I am getting this same error 1603 message. I sent someone a pinned location and when they tried to open the kmz file it stated that I was sending an old version that they could not open. I tried to update my Google Earth but the only option is to download it.
When trying to install Google Earth the following message appears and terminates installation: "The installer encountered error 1603". I have read the forum for possible similar issues but have not yet found a successful solution.
Error 1603 when you try to install Google Earth or Earth pro in the computer and will not get installed. While trying to install the latest version of Google Earth, it pops up a message about “error 1603” and the install fails. The error message appears as below.