Mouse tracking speed stuck on slowest setting since 10.12.4 update I use an external usb mouse/keyboard when I use my Mac (and have been for some time without any problems). Since the C-Error 10.12.4 update, my Macbook Pro no longer allows me to set/save my Mouse Tracking Speed in the System Preferences and the mouse tracking speed is stuck on slowest speed.

When I open System Preferences, the mouse tracking speed slider is on ‘Slow’.  For a moment after I pull the slider to a higher speed, the mouse speeds up but then immediately returns to the slowest speed, though the slider stays where I set it.

The slider stays at my setting until I exit the System Preferences, whilst the mouse moves as though it's set to the slowest speed.  When I return to the System Preferences, after closing it, the mouse tracking speed slider is back to the ‘Slow’ setting.

Moving the slider again repeats what I described above.

I have tried using defaults write -g com.apple.mouse.scaling 8 but that has no effect after logging out and back in.  Using defaults read -g -g com.apple.mouse.scaling returns 2 initially, and after I set the speed to fast, it shows 3 on subsequent reads.  I have also reset NVRAM but to no avail. However, resetting NVRAM had the, undesired, effect of wiping my UEFI boot settings and now I can't boot into my Ubuntu partition.  (Not very happy at the moment!)

The interesting thing is that while my Mac is on the login screen, the mouse tracks exactly how I want it (perhaps too fast since I've been playing with the settings).

Is there any other command I can issue in the terminal to get my mouse working the way I like it and how it was before this latest update?
I ran into this problem this morning. After trying several things which themselves did not work I finally found the solution:

Uninstall SmoothMouse

The app is no longer supported by the developers and they recommend removing it.


  To Uninstall SmoothMouse  
  
  
  System menu (the Apple logo) -> System Preferences
  Find SmoothMouse in the bottom section and open it
  Open the About tab in the SmoothMouse settings and click Uninstall.
  


You might need to restart afterwards but that fixed it for me.