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Hi Sarah,

You need to uninstall AutoCAD with "Remove AutoCAD" application, then install it again using original installer:

http://efulfillment.autodesk.com/NET17SWDLD/2017/ACDMAC/ESD/Autodesk_AutoCAD_2017_Mac_OSX.dmg?authpa...

Then you can install the last Update again.

Maxim