If you run into the “Unable to Open Kernel Device ‘\.\VMCIDev\VMX’” error on your Windows device when you try to run your virtual machine, you’re in luck. This article would show you how to fix it in a few minutes.

How to Fix the “VMware Workstation Error: Unable to Open Kernel Device ‘\.\VMCIDev\VMX’” Error

So, what’s triggering this error? Thankfully, the error message itself gives us enough information to pinpoint the cause.

The “VMCI” part of the error stands for “Virtual Machine Communication Interface.” It provides efficient and fast communication between a virtual machine and the host operating system, and between two or more virtual machines on the same host. The VMCI is present in all virtual machine providers like VMWare, VirtualBox, and Hyper-V.

As such, to fix the problem, we have to tackle the VMCI. So, let’s get into fixing this error.

1. Fixing the VCMI Error

To solve this error, you need to edit the VMX file of the virtual machine that pops the error. A VMX file contains the hard disk, memory, and processor limit settings of the virtual machine.

Locate the folder of the virtual machine. Search for the VMX file. It doesn’t necessarily need to end with the VMX suffix. Search for an icon that looks like three white pages. Open the file with Notepad or any text editor. Search for the line with vmci0. present. Change the value from “TRUE” to “FALSE”. Save and close the file. Restart your computer.

Your virtual machine should run without hitches now.

2. Uninstall and Reinstall the VMware Workstation

If the first fix doesn’t work, uninstall the VMWare workstation program and reinstall it. This would reset it, and then you can use your virtual machines again. Here’s how to uninstall programs on Windows 10 and some different ways to uninstall software in Windows 11.

The VMware Workstation Error Is Now Fixed

Now you know how to fix this VMWare error. We hope that the steps above have completely solved your problem and that your virtual machines are up and running. However, if the error persists, you could try contacting the VMWare support team.