Depending on whether you actually need the serial port or just want the error to go away, use one of the following three methods. Method 1: Remove the Serial Port (Recommended)
In a real Cisco router, Serial interfaces use . If no cable is plugged in, the interface remains "down/down." However, emulators are not real circuits. If an emulator tried to auto-detect every possible connection at boot, it would slow down the entire lab startup process. virtual device serial0 will start disconnected
Most fixes involve aligning the VM's expectations with VMware's global settings. Depending on whether you actually need the serial
Alternatively, to remove it entirely via text, delete all lines starting with serial0 . the interface remains "down/down." However
Look for lines like:
"Virtual device serial0 will start disconnected"