You have multiple versions (e.g., AutoCAD 2018 installed on D: drive but update applied to default location on C:). Solution: Use the /p parameter from command line to point the installer to the correct path:
How to Fix 'Your AutoCAD License Is Not Valid' [8 Solutions] - ZWSOFT Autocad 2018.0.2 Update 64-bit Download
Issue 1: "The update cannot be installed because the public key is invalid" You have multiple versions (e
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If you have the Autodesk Desktop App installed (usually found in your Windows System Tray): Open the app. Click on the tab. Find the 2018.0.2 Update in the list and click Update . 3. Direct Download Links
The installer will extract files to your temporary folder.