Many linux systems don&#x27;t even support in-place upgrades between major versions. And I don&#x27;t think i&#x27;ve ever had one work where nothing broke.<p>RHEL only started supporting it for the transition between 6 and 7 on a like 3 architectures on one edition.<p>And OSX has it&#x27;s share of issues. For me personally, updating to El Capitan was the worst upgrade processes i&#x27;ve done in recent memory. From not running the installer but giving no issues, to not finding the harddrive during the install process, to corrupting the current install of yosemite, to bluetooth being broken after the upgrade, and i can&#x27;t get wifi speeds over 1mbps.<p>A clean install solved all of that, but that&#x27;s pretty normal with every single OS i&#x27;ve ever encountered.<p>It&#x27;s not a question of being &quot;more careful&quot;, it&#x27;s that writing software in a way that it can be in-place upgraded to something you don&#x27;t know will exist at the time is EXTREMELY HARD! I really feel it&#x27;s one of the big &quot;unsolved problems&quot; in computer science and i don&#x27;t see it being solved any time soon.