I just updated my CCleaner Pro after installing Mac OSX 11.3.1 Big Sur a couple of months ago. I noticed that the top right corner of my CCPro lists my operating system as the OLD OSX 10.16 (Catalina) instead of OSX 11.3.1 Big Sur. (Please see the screenshot attached.) I don't understand this. Can someone explain it to me? Does it matter, or should I just ignore it? Thanks!
Big Sur is both v10.16 and v11.##
Apple decided to change the OS version to 11 at a late stage just before final release.
The official explanation why it is both is that it's for compatibility reasons.
That's so some apps will see it as a minor update rather than as a whole new operating system.
So depending on just where in the OS you look for the version number, and how you ask, it will tell you different things.
Some variables will tell you it's v10.16, other variables will tell you it's v11.#, some variables even give you the different answer depending on how you ask.
Quote<div class="ipsQuote_contents ipsClearfix" data-gramm="false"> <p> If the calling environment sets the variable SYSTEM_VERSION_COMPAT=1 then Big Sur will return 10.16 as its version number; With that variable absent or set to 0, the version returned will be 11.0. This should ensure that those who need compatibility with the previous version numbering can obtain it. </p> </div>
So CCleaner could change how it calls the version number so it would then show OS X 11.#; but that could then give problems for those who are still using OS X 10.# versions.
PS. Catalina was the last 'real' OS X 10 at v10.15.
Thanks, nuked! Great answer!