Do not just reinstall AutoCAD. The "20 generic license checkout error" is rarely solved by a full reinstall. Instead, follow this tiered approach.
A developer on the night shift had updated a virtual machine and neglected the time sync. The license server, trustful as any bureaucracy, denied requests that seemed from the future. Jonah imagined the server as an old librarian refusing entry to those without proper timestamps on their permits. He corrected the NTP settings. The servers re-aligned. The clock hands returned to an honest, shared present. 20 generic license checkout error autocad