The problem occurs on various OS X and MacOS versions (reported on OS X Mountain Lion 10.8.2, OS X Mavericks, OS X Yosemite, OS X El Capitan, macOS Sierra).
The Cause of the Problem
In most cases, when users are experiencing this problem, the other (3-finger and 4-finger) gestures work just fine. Only the two-finger scrolling does not work properly. That indicates that there is not a hardware issue with your touchpad. (Make sure if others gestures works on your touchpad.) This problem seems to happen after an OS update. In that case, more than likely this is caused by the global preferences which hold touchpad information. What happens is the computer keeps the old settings, while the updated OS requires new ones. This software misunderstanding leads to a non-working touchpad. Here is how can you fix that.
Fix #1: Use Terminal to Enable 2-Finger Scrolling
By default, global preference settings are hidden in OS X and macOS. However, you can use Terminal to enable them and fix the two-finger scrolling gesture. defaults write -g com.apple.trackpad.scrollBehavior 2 Now, try the 2-finger scrolling gesture. If your touchpad is not working, continue with the next fix.
Fix #2: Adjust System Preferences
Fix #3: Disable 2-Finger Swipe Between Pages
This method helps if your 2-finger scrolling feature doesn’t work in web browsers (Chrome and Firefox). I hope we helped you to fix your touchpad scrolling feature. Now, let us know what did work for you, in the comment section below.
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