EVE-NG handles this more elegantly, but the principle is the same.
If you tell the VM to connect to COM1 on the host, but that port is already in use by another host application (e.g., a real terminal program, a PLC programming tool, or another VM), VMware will not forcibly steal the port. Instead, it starts the VM with that device disconnected and logs this warning.
To improve boot performance and prevent unnecessary I/O delays, serial0 (the primary virtual serial device) now starts in a disconnected state by default. The serial interface will only become active after an explicit connection is established by the user or guest OS.
If you need serial0 active at boot:
Some VM templates or quick-creation wizards add a serial port by default but leave it disconnected. This is common in Linux VM templates that include a legacy console serial port that may not be needed.
