Hi Ernesto,
The ArcGIS 10.3 setup package is designed to detect and upgrade an existing installation of the same ArcGIS product. The settings for the installation location and authorization information are retained in the upgrade.
Existing ArcGIS 10.1-10.2.2 authorization numbers will work with ArcGIS 10.3.
It is recommended that you use setup.exe to upgrade ArcGIS Server to 10.3.
If you encounter the following error, you launched setup.msi instead of setup.exe:
"Upgrade patch not found. ArcGIS 10.1 for Server cannot be directly upgraded to10.3 without this patch.
Upgradation of ArcGIS 10.3 for Server
Thanks,
Jay
Think Location