when the software can't find or use the serial port assigned to the virtual machine. In recent updates (Fusion 13.5+ and Workstation 17.5+), this is most commonly caused by the removal of support for ThinPrint (virtual printing). Broadcom support portal Why this is happening Discontinued ThinPrint Support

If you are a standard user running Windows or Linux desktops, simply removing the Serial Port from the settings is the permanent solution.

: The .vmx configuration file contains parameters for serial0 that the hypervisor cannot process, such as an invalid file type or destination. How to Fix It Method 1: Disable Virtual Printing (Recommended)

This warning can appear if you are trying to use remote serial ports (e.g., via Telnet) but your license (like the free version of ESXi) does not support it [ Remove the Hardware: If you do not require a serial console, go to Edit Settings

If you are just running a standard OS (Windows, Linux, macOS) and are not debugging kernel panics, you likely do not need this device. Removing it will clean up your logs and slightly improve boot speed.