If you are using ESXi, you must reload the VM configuration via the command line so the hypervisor recognizes the manual change:
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
Change serial0.present = "TRUE" to serial0.present = "FALSE" . Save the file and reload the VM in VMware. If you are using ESXi, you must reload
The message indicates that the virtual device associated with serial0 (the first virtual serial port in many virtualization platforms) is not connected when the VM starts up. This disconnection can occur for several reasons: Change serial0
When a virtual machine boots, the hypervisor reviews the configuration file (the .vmx file) and attempts to initialize all listed hardware components.