For those of you who've already gotten Beta Preview or Developer Preview access to Mac OS X 10.10 Yosemite, I highly recommend installing it on a separate partition on your hard drive. There have been many reported bugs and even blank gray screens that prevent access to the system, so if you install over your current OS, you're risking having to boot into recovery or reinstall from the ground up.

Niresh Mac OSX Mavericks 10.9 DVD ISO Free Download - All Nov 23, 2019 Mac OS X Mavericks 10.9 ISO and DMG Image Download for May 21, 2020 Get your Mac ready for Mavericks (OS X 10.9) | Macworld

Video stops working with all third party apps such as Bluejeans with update to Mac OSX 10.9.1 (MacBook Air 6). It works with all the native apps within Mac. User affected with this issue, will see a "Camera not detected" message on the self view video and the video transmission breaks.

Aug 23, 2018

The name of your macOS user account and the name of your home folder must both be the same. Changing these names does not change or reset the password of your user account.. Because doing this incorrectly could damage your account and prevent you from logging in, you should back up your important data before proceeding.

OS X Mavericks (version 10.9) is the tenth major release of OS X (since June 2016 rebranded as macOS), Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Mavericks was announced on June 10, 2013, at WWDC 2013, and was released on October 22, 2013 worldwide.. The update emphasized battery life, Finder improvements, other improvements for power users, and continued macOS (/ ˌ m æ k oʊ ˈ ɛ s /; previously Mac OS X and later OS X) is a series of proprietary graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers.Within the market of desktop, laptop and home computers, and by web usage, it is the second most widely used desktop OS, after Microsoft Windows.