The vmmon kernel module is necessary for virtualization, and when VMware Workstation or VMware Player cannot access it, the error message “Could not open /dev/vmmon: No such file or directory in Vmware” usually appears. At Bobcares, we assist our customers with several VMware queries on a daily basis as part of our Server Management Services.

Overview

1. Resolving the “Could Not Open /dev/vmmon: No Such File or Directory” Error in VMware
2. Impacts of the Error
3. Common Causes and Fixes
4. Prevention of Future Errors
5. Conclusion

Resolving the “Could Not Open /dev/vmmon: No Such File or Directory” Error in VMware

The error message “Could not open /dev/vmmon: No such file or directory” is a common issue encountered by users of VMware Workstation or VMware Player. This error indicates that the vmmon kernel module, essential for virtualization, cannot be accessed. Understanding the causes and solutions to this error can help users restore functionality and avoid downtime in their virtual environments.

The syntax of the error is clear:

This message suggests that the system cannot locate the vmmon device file. Usually, when the vmmon kernel loads, the device file will also be present. If the module fails to load or is not present, VMware cannot interact with virtual machines, rendering the software inoperable for virtualization tasks.

Impacts of the Error

The consequences of this error can be significant:

Inability to Start Virtual Machines: Users cannot launch or run any virtual machines, making the software unusable.

Loss of Productivity: Downtime can hinder workflow, particularly for those relying on virtual environments for development or testing.

Potential Data Loss: Users may risk losing unsaved data or progress if they cannot access their virtual machines.

Common Causes and Fixes

Here are the primary causes of the error along with their respective fixes:

1. Missing Kernel Module

Cause: The vmmon module not loading, which is crucial for VMware’s operation.

Fix: To load the vmmon module, open a terminal and run:

bash

sudo modprobe vmmon

If there is no output, the module has loaded successfully. We can verify this by running:

bash

lsmod | grep vmmon

If we see vmmon listed, the module is active. If the command fails, we may need to reinstall or recompile the VMware modules.

2. Incorrect Kernel Headers

Cause: Installed kernel headers might not match the currently running kernel version.

Fix: Install the correct kernel headers by executing:

bash

sudo apt install linux-headers-$(uname -r)

After installation, rebuild the VMware modules with:

bash

sudo vmware-modconfig --console --install-all

To verify the headers are correctly setup, we must check:

bash

dpkg -l | grep linux-headers

3. Secure Boot Enabled

Cause: Systems with Secure Boot enabled cannot load unsigned kernel modules.

Fix: We need to sign the vmmon and vmnet modules. Follow these steps:

Generate a key pair:

bash

openssl req -new -x509 -newkey rsa:2048 -keyout MOK.priv -outform DER -out MOK.der -nodes -days 36500 -subj "/CN=VMware/"

Sign the modules:

bash

sudo /usr/src/linux-headers-$(uname -r)/scripts/sign-file sha256 ./MOK.priv ./MOK.der $(modinfo -n vmmon)
sudo /usr/src/linux-headers-$(uname -r)/scripts/sign-file sha256 ./MOK.priv ./MOK.der $(modinfo -n vmnet)

Import the key:

bash

sudo mokutil --import MOK.der

We’ll be prompted to set a password. After rebooting, follow the instructions to enroll the key. After rebooting, check if the modules are loaded:

bash

lsmod | grep vmmon

4. VMware Installation Issues

Cause: VMware may not have installed correctly, or the necessary modules weren’t built during installation.

Fix: Reinstall VMware Workstation or Player.

Uninstall VMware:

bash

sudo apt remove --purge vmware-workstation

Reinstall VMware by downloading the latest installer from the official VMware website and running:

bash

sudo bash VMware-Workstation-Full-*.bundle

Ensure we have the necessary build tools and headers:

bash

sudo apt install build-essential linux-headers-$(uname -r)

Rebuild VMware modules with:

bash

sudo vmware-modconfig --console --install-all

Verify that VMware services are running:

bash

sudo systemctl status vmware

5. Kernel Updates

Cause: After a kernel update, the VMware modules may require rebuilding.

Fix: After updating the kernel, open a terminal and run:

bash

sudo vmware-modconfig --console --install-all

This process will compile and install the necessary VMware modules for the new kernel. Verify the modules are loaded correctly with:

bash

lsmod | grep vmmon

Prevention of Future Errors

To avoid encountering this error again, consider the following preventive measures:

1. Regular Updates: We must keep the system and VMware software updated to the latest versions to ensure compatibility with kernel changes.

2. Kernel Headers: We must always install the corresponding kernel headers when updating the kernel.

3. Secure Boot Management: If using Secure Boot, also, ensure that all necessary modules are signed properly to avoid issues during boot.

4. Automate Module Loading: We can also consider adding the modprobe vmmon command to the system’s startup scripts to ensure the module is loaded automatically on boot.

[Need to know more? Get in touch with us if you have any further inquiries.]

Conclusion

The “Could not open /dev/vmmon: No such file or directory” error can disrupt the virtualization experience in VMware. By understanding the causes and implementing the suggested fixes, we can effectively resolve the issue and minimize future occurrences. Maintaining an updated environment and being proactive about system configurations will ensure smoother operation and enhanced productivity in the virtual tasks.