Most common installation problems with Macintosh?

It's rare to have an installation issue on Macs today due to how easy it is to install programs on them with how they are setup. The only real install issue I can think of would be if you have an older Mac and a trying to update certain software that doesn't meet the proper system requirements such as your Mac OS version is too old to handle an updated piece of software you are trying to install, in which case, you won't have a problem installing, you just simply won't be able to install it and it will tell you the reason.