If your workflow requires a functional serial port (for example, kernel debugging or interfacing with network equipment via a console), you must redirect the port to a valid resource instead of a nonexistent physical host port. the VM and open its Settings . Select the Serial Port .
The easiest way to resolve this is to remove the legacy printer device that is causing the conflict. your virtual machine completely. Open the Virtual Machine Settings . Find Printer in the list of hardware devices. Select it and click Remove . Click OK and restart the VM. Option 2: For VMware Workstation Users
Verify that the pipe name matches your debugging client configuration exactly and that firewall rules permit the connection. Check the Connect at power on box. Click Save and test the VM boot sequence. Method 3: Modify the VMX Configuration File Manually
When powering on a virtual machine (VM) in VMware vSphere, ESXi, or Workstation, you may encounter the warning message: virtual device serial0 will start disconnected
Depending on whether you actually need to use a serial port within your virtual guest OS, choose one of the following solutions.
If you’d like, I can guide you through configuring a named pipe for advanced debugging, or help with mapping the physical port to a host device. Let me know which you need!
The VM is set to connect to a named pipe or a physical port that is disconnected. How to Fix the "Serial0" Warning If your workflow requires a functional serial port
A: Upgrades often deprecate or remove features. Fusion 13.5 removed ThinPrint entirely, causing the virtual printer serial port to be invalid. Similarly, upgrading Workstation may carry over outdated .vmx settings that trigger the warning.
: Another background application or virtual machine may already hold an exclusive lock on the specific physical serial port or named pipe you are trying to deploy.
If your workflow requires one of these setups, ensure that the serial0.fileType or physical port mapping in your settings matches an existing, accessible path on your host machine to prevent the disconnected error. The easiest way to resolve this is to
What Does "Virtual Device Serial0 Will Start Disconnected" Mean?
The VM configuration is mapped to a physical COM port (e.g., COM1) on the host machine, but the host machine lacks a physical serial port. This is incredibly common with modern servers and laptops that dropped legacy serial ports years ago.