A student attempted to build a Frame Relay switch using a Cisco 3640 in GNS3. After configuring the Frame Relay map statements and inverse ARP, the PVCs remained inactive. The student spent six hours checking DLCI numbers and encapsulation types.
The root cause? The console log from boot clearly showed: "Virtual device serial0 will start disconnected" and "Virtual device serial1 will start disconnected". The student had never connected the cables from the router to the Frame Relay switch.
Moral of the story: Always read the console boot messages. That "disconnected" line is not a warning; it is a direct status report.
Related search suggestions I can run for more detail: "virtual device serial0 will start disconnected libvirt", "serial0 will start disconnected QEMU", "enable serial console libvirt getty ttyS0".
The error message "virtual device serial0 will start disconnected" typically appears in VMware environments when a virtual machine (VM) is configured with a serial port that it cannot properly initialize at startup. This is often a non-critical notification rather than a fatal error, but it can be annoying or indicate a configuration mismatch. Why This Happens
Virtual Printing Conflict: A common cause is the "Virtual Printing" feature. If this feature is globally disabled on your host system but enabled in the VM settings, VMware attempts to use serial0 for the printer connection and fails, triggering the message.
Missing Physical Hardware: The VM might be configured to connect to a physical serial port (COM1, etc.) on the host that doesn't exist or is currently being used by another application.
Manual VMX Edits: If you have manually edited the .vmx file to add a serial port but haven't correctly defined the pipe or file it should connect to, the device will remain disconnected. How to Fix It 1. Disable the Serial Port (If Not Needed)
If you aren't intentionally using a serial device or virtual printer: Shut down the Virtual Machine.
Go to VM > Settings (or right-click the VM in the library and select Settings). Select Serial Port from the Hardware tab.
Uncheck Connect at power on or simply click Remove to delete the device entirely. 2. Resolve Virtual Printing Issues If the message specifically mentions virtual printing: In the VM Settings, look for the Printer device.
If you don't need to print from the VM, Remove the Printer device.
Alternatively, go to Edit > Preferences in the VMware Workstation/Player menu, navigate to Devices, and ensure "Enable virtual printers" is checked if you do want to use this feature. 3. Adjust the .vmx Configuration
For advanced users needing the port to start connected (e.g., for debugging or specific hardware mapping), ensure these lines exist in your .vmx file: serial0.present = "TRUE" serial0.startConnected = "TRUE"
Ensure the serial0.fileType matches your intent (e.g., "device", "pipe", or "file"). USB Serial Port kinda working | Fusion - Broadcom Community
How to Fix: "Virtual device serial0 will start disconnected" virtual device serial0 will start disconnected
If you just powered on your VMware virtual machine and were greeted by the warning "Virtual device serial0 will start disconnected,"
you aren’t alone. While it sounds like a critical hardware failure, it is usually just a configuration "ghost" left behind by old software or missing physical ports. What Does This Error Actually Mean?
The error indicates that your VM is configured to look for a serial (COM) port on your physical computer, but it can’t find one to "handshake" with. Because the VM can't establish this link, it simply starts with that specific virtual device disabled. Common Causes The "ThinPrint" Legacy:
Most modern occurrences are caused by a recent VMware update (Workstation 17.5+ or Fusion 13.5+). VMware discontinued support for
(a virtual printing technology), but many older VMs still have "Printer" devices in their settings that rely on Missing Physical Hardware:
You have a Serial Port added to your VM settings, but your actual laptop or desktop doesn't have a physical COM port. Conflict with Host Drivers:
If you are using a USB-to-Serial adapter, the host OS might not have the correct drivers (like CH340 or FTDI) installed, making the port "invisible" to the VM. How to Fix It Method 1: The Quick GUI Fix (Recommended)
The easiest way to stop this message is to remove the device that is trying to use the serial port. the virtual machine. VM > Settings (or right-click the VM and select
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 the GUI doesn't work or you are on an encrypted VM, you can manually "clean" the configuration file.
Navigate to your VM's folder on your hard drive and locate the Open it with a text editor like Search for lines starting with If you see serial0.fileType = "thinprint" , you can safely delete all lines or change serial0.present the file and try powering on again. Method 3: Fixing Real Serial Connections If you actually
the serial port for a project (like Arduino or industrial hardware): Check Host Drivers: Ensure your host machine recognizes the device in Device Manager (Windows) or ls /dev/tty* Update Connection Mapping:
In VM Settings, ensure the "Connection" is set to the correct physical port (e.g., /dev/ttyUSB0 In 90% of cases, this error is just
complaining that it's been retired. Deleting the "Printer" hardware from your VM settings is the fastest way to get a clean, error-free boot. specific platform like LinkedIn or a technical documentation site?
Parameter "serial0.fileType" has an invalid value "Thinprint 10 Nov 2023 — A student attempted to build a Frame Relay
| Platform | Typical Reason |
| :--- | :--- |
| VMware Workstation/Fusion | The serial port is set to "Use named pipe" or "Use output file", but the other end (e.g., a debugger like WinDbg) hasn't connected yet. |
| VirtualBox | Serial port is enabled with "Port Mode" set to "Disconnected". |
| GNS3 / EVE-NG | The virtual router or switch has a serial interface (e.g., serial0/0), but it's not linked to another device's serial interface via a cable. |
| QEMU | The -serial option is used without a backend (e.g., -serial null or -serial unix:/path,server=off). |
To remove: Select the serial port and click Delete.
If you have ever fired up a Cisco router in Dynamips, GNS3, EVE-NG, or Cisco Packet Tracer, you have likely seen the console output slowly crawl by until it halts at a seemingly concerning line:
"Virtual device serial0 will start disconnected"
For many students, this message triggers an instinct to panic. Is the router broken? Is the image corrupted? Will Serial0/0 ever come up?
The short answer is: No, your router is not broken. Everything is functioning as designed.
However, understanding why this message appears, what it actually means for your virtual lab, and how to resolve the underlying connectivity issue is crucial for building functional network topologies. This article provides a deep dive into the causes, step-by-step troubleshooting, and permanent solutions for the "Virtual device serial0 will start disconnected" message.
If you are a hardcore Dynamips user on Linux, you can edit the .net file directly. Change this:
[[router R1]]
image = c7200.bin
serial0 = "disconnected"
To this:
[[router R1]]
image = c7200.bin
serial0 = "R2 serial0"
This tells Dynamips to create a direct serial cable between the two virtual devices on boot.
"virtual device serial0 will start disconnected" is normal behavior when you've enabled a serial port but not defined a live connection. It does not indicate a problem with your virtual machine or device.
The error message "Virtual device serial0 will start disconnected"
typically occurs in VMware Fusion or Workstation after an update (specifically VMware Fusion 13.5 Workstation 17.5 ) because support for virtual printing has been discontinued
. When the software starts, it tries to initialize the serial port formerly used for ThinPrint, fails because the driver is missing, and displays this warning. Root Cause In previous versions, used a virtual serial port (
) to handle "Virtual Printing" (ThinPrint). Following the removal of this feature in late 2023 updates, legacy virtual machine configurations still contain entries for it, leading to an invalid parameter error: serial0.fileType = "thinprint" How to Resolve the Issue Method 1: Using the GUI (Recommended for Workstation) Power off the virtual machine. VM Settings Select the and save your changes. : In VMware Workstation, go to Preferences and uncheck "Enable virtual printers" to prevent it globally. Broadcom support portal If you have ever fired up a Cisco
Method 2: Manually Editing the .vmx File (Recommended for Fusion)
If the device doesn't appear in the settings menu (common in Fusion 13.5+), you must manually edit the configuration file: Broadcom Community and ensure the VM is powered down. Locate your virtual machine's file (usually inside the VM bundle).
Open the file with a text editor (like TextEdit on Mac or Notepad on Windows). Find and delete the following lines: serial0.fileType = "thinprint" serial0.fileName = "thinprint" serial0.present = "TRUE" (Note: You can also set this to Save the file and restart the VM. Broadcom support portal Important Note for Encrypted VMs If your VM is fully encrypted
(often required for Windows 11 due to TPM), you may not be able to edit the file directly as it is encrypted . In these cases, the warning may persist until
provides a native patch, though the VM will generally continue to function normally if you simply click "OK" or "X" on the message a VM so you can edit its configuration?
The error message "Virtual device serial0 will start disconnected" in VMware (Workstation or Fusion) most commonly occurs because support for ThinPrint (virtual printing) has been discontinued in recent versions like Workstation 17.5 and Fusion 13.5. Primary Fixes Remove the Printer Device (Easiest Method): Shut down the virtual machine. Go to VM Settings > Hardware tab. Select the Printer device and click Remove. Click OK and restart the VM.
Edit the .vmx Configuration File (Advanced):If the device isn't visible in the GUI or the message persists, you can manually remove the offending lines from your VM's configuration file: Open your VM's folder and locate the .vmx file. Open it with a text editor (like Notepad or TextEdit). Find and delete the following lines: serial0.fileType = "thinprint" serial0.fileName = "thinprint" serial0.present = "TRUE" Save and close the file, then restart your VM. Troubleshooting Physical Port Conflicts
If you actually need to use a serial port and the error says "no corresponding device available on the host," try these steps:
Verify Host COM Port: Ensure the serial port (e.g., COM1 or /dev/ttyS0) is enabled in your host's BIOS and is not being used by another application (like Putty).
Manual Mapping: Manually edit the .vmx file to point to the correct host port by changing the serial0.fileName to the specific port name, such as COM3 on Windows or /dev/tty.USA19H3d2P1.1 on Mac.
For more detailed guides, you can visit the Broadcom/VMware Knowledge Base or the VMware Fusion community discussions. If you’d like, let me know:
Which VMware product and version you are using (e.g., Workstation 17.5)?
Do you actually need to use a serial device (like a console cable), or do you just want the error to go away? I can provide the exact steps for your specific version. USB Serial Port kinda working | Fusion - Broadcom Community
Connecting from the host:
Automating access:
Emulating unplugged hardware: