Virtual Device Serial0 — Will Start Disconnected

Back up the .vmx file.

: If the VM properties dictate using an absolute physical COM port (like COM1 or /dev/ttyS0 ) on the host machine, the hypervisor looks for that hardware during initialization. If your modern laptop or desktop lacks an actual serial interface, the mapping fails immediately.

If you are managing VMs remotely, using ESXi, or prefer editing configuration files directly, you can fix the issue by modifying the VM’s .vmx file.

This article applies to VMware Workstation Pro/Player 15–17, VMware Fusion 11–13, and ESXi 6.5 through 8.0. For older versions, the behavior and fix remain fundamentally the same. virtual device serial0 will start disconnected

For most modern operating systems, serial ports are legacy components. Unless you are debugging a kernel, setting up a specialized console, or connecting to legacy industrial equipment, a disconnected serial port will not impact your VM's performance. How to Fix the Error

In virtualization, a "Serial Port" is a virtualized version of the old-fashioned COM ports. It allows the guest operating system inside the VM to communicate via a serial protocol. When you see this error, it means: Your VM configuration file ( ) defines a serial port ( serial0s e r i a l 0

If you do not need the serial port, or if it is misconfigured, telling the machine not to connect it at startup will eliminate the error. Open the virtual machine's (VM -> Settings). Click on Add/Hardware and select Serial Port . Uncheck the option "Connect at power on" . Click OK and restart the VM. 3. Remove the Unused Serial Port Back up the

To help narrow down the cause of this error, could you tell me:

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.

in the hardware list. If you don't need to print from your VM, select it and click If there is a Serial Port listed that you don't use, select it and click and restart the VM. Method 2: The .vmx File Surgery If you are managing VMs remotely, using ESXi,

When powering on a virtual machine (VM) in VMware Workstation or ESXi, you might encounter a persistent warning message:

The VM is configured to use a physical serial port (e.g., COM1 on the host) that does not exist or is unavailable.

Understanding the VMware "Virtual device serial0 will start disconnected" Error

serial0.present = "TRUE" serial0.startConnected = "TRUE" serial0.fileType = "file" serial0.fileName = "/vmfs/volumes/datastore1/vm_folder/serial.log" Use code with caution.

is set to "thinprint" incorrectly. You can often resolve this by following the VMware Knowledge Base Article 95329 or manually editing the file to ensure serial0.present = "FALSE" if you don't need the port [ For VMware ESXi/vSphere Users: Check Licensing: