Virtual Device Serial0 Will Start Disconnected ^new^

This warning message (or log entry) typically appears in VMware products (like VMware Workstation, Player, or ESXi). It indicates that the virtual machine is configured to have a serial port, but the host computer cannot connect to it—usually because the designated file or device path does not exist yet.

1. Select the serial port.
2. Choose Output to file.
3. Set file path to nul (Windows) or /dev/null (Linux/macOS).
4. Check Connect at power on.
5. Click OK.

How to "fix" it (if you want the port to be connected)

If you need serial0 active at boot:

• libvirt: virsh console (or virsh attach-device)
• VirtualBox: enable host pipe or file for the serial port and reconnect.

1. Shut down the Virtual Machine.
2. Go to the menu bar: Virtual Machine > Settings.
3. Click on Ports & Devices (or look for a Serial Port icon in the sidebar).
4. Uncheck Connected or Connect at power on.
5. Close the settings window and start the VM.

Quick Summary

• Severity: Low (Usually a warning, not a fatal error).
• Meaning: The VM is trying to initialize a serial port, but the destination (file or physical port) isn't ready, so it defaults to a "disconnected" state.
• Common Fix: Edit VM settings to create the output file or remove the serial port if unused.

Serial0                   unassigned      YES unset  administratively down down

Missing Physical Hardware: The VM is set to connect to a physical COM port on your host machine that does not exist or is currently being used by another application. virtual device serial0 will start disconnected