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    • Virtual: Device Serial0 Will Start Disconnected

    The message indicates that the virtual device associated with serial0 (the first virtual serial port in many virtualization platforms) is not connected when the VM starts up. This disconnection can occur for several reasons:

    Option A: Remove the Serial Port (if unused)

    Option B: Configure it to Connect at Power On

    If you want the port active but connected to nothing (to suppress the warning), you must trick VMware into thinking it has a valid backing:

    The VM will now think it has a valid serial port and will not log the disconnected warning. virtual device serial0 will start disconnected

    Option C: Use Named Pipe to Nowhere (Advanced)

    If you unchecked "Connect at power on" but still get the message:

    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.

    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 message indicates that the virtual device associated

    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.

    Here is a comprehensive guide on why this happens and how to resolve it.

    If you are building massive topologies (e.g., 50+ routers for CCIE studies), seeing "virtual device serial0 will start disconnected" for every single router can clutter your console logs. Here is how to mute or manage it:

    Q: Does this warning affect clone or snapshot operations?
    A: No. Snapshots and clones remain unaffected. The disconnected serial port does not hold any state. Option B: Configure it to Connect at Power

    Q: Can I hide the warning without removing the serial port?
    A: In VMware Workstation, you cannot suppress warnings globally. The only way is to connect the port to a valid target (file or pipe) or remove it.

    Q: Does this appear in VirtualBox or Hyper-V?
    A: VirtualBox calls it "Serial Port 1 – disconnected" and Hyper-V shows no explicit warning unless you open guest settings. The behavior is VMware-specific in phrasing but functionally similar.

    Q: What if I have multiple serial ports (serial1, serial2)?
    A: The same rule applies. Each disconnected port will log a separate warning.

    Even after you connect the virtual cable, you might still face a down/down or up/down status. After fixing the "start disconnected" message, ensure you have a clock rate set on the DCE side.

    In a real lab, service providers provide the clock. In an emulator, you must provide it.

    Within 30 seconds, both interfaces should transition to up/up. The original disconnected message is now a relic of the boot sequence.