As announced on the official AutoCAD blog, Autodesk introduced a problem with the 2018.0.1 Update, and then resolved the issue by releasing the AutoCAD 2018.0.2/AutoCAD LT 2018.0.2 Update. As this update fixes a defect that would cause the product to not start, it is critical for users who installed the initial 2018.0.1 Update to install the AutoCAD 2018.0.2/AutoCAD LT 2018.0.2 Update as soon as possible and before June 1, 2017.
You should be able to obtain this update from the Autodesk Desktop App, unless you have chosen to not use this app or your company blocks it, etc. – in which case you will have to go find it using a few more steps.
