Sometimes, you need to access the /Library folder that’s in your home folder (the one with the house icon and your user name). For a while now, this folder has been hidden.
Previously, you could access this by press the Option key, then selecting the Go menu in the Finder. The Option key would add Library to the list of locations in that menu. But this was changed when 10.12.2 was released. Instead of pressing the Option key, you need to press the Shift key. You can also open that folder more easily by pressing Command-Shift-L.
Not a big deal, but if you’re used to using the Option key, you may be surprised to find it doesn’t work any more.
You can also ensure that this Library folder displays by entering your home folder, then displaying the View Options window (View > Show View Options), and checking Show Library Folder.
H/t Michal Tsai.