Common VMware errors, issues, and troubleshooting solution

VMware is one of the most widely used tools in the virtualization world. Businesses of all sizes and industries use it to save costs and create more flexible IT infrastructures. But like any software, VMware isn’t perfect. Users often run into errors and issues that can disrupt their virtual machines or even affect whole networks.

This article goes over some of the most common VMware problems, explains why they happen, and shares straightforward solutions to help you troubleshoot them.

What is VMware?

VMware is a virtualization software that allows users to create multiple virtual machines (VMs) on a single physical server. The VMs share the hardware resources of the physical server, such as CPU, memory, and storage, but each operates as an independent computer, with its own operating system and applications.

This virtualization of physical resources is made possible via a hypervisor, a layer of software that sits between the hardware and the virtual machines. The hypervisor allocates CPU, memory, storage, and other resources to the virtual machines as needed. This setup lets each VM operate independently, even though they share the same physical resources. So, whether you’re running Windows, Linux, or other operating systems, they can all run on a single server, thanks to the hypervisor.

Key VMware features

• Snapshots: Save the current state of a VM so you can revert back if needed.
• Cloning: Create exact copies of VMs for testing or backup.
• Resource management: Allocate and adjust resources like CPU and memory as needed.
• High availability: Create failover plans that ensure applications remain accessible even if a VM fails.
• Scalability: Easily add more VMs or resources on the fly as business needs grow.
• Storage virtualization: Pool physical storage devices into a single, logical storage resource.

VMware installation and configuration related issues

Let’s start by looking at some common issues users face while installing and configuring VMware.

VMware installer fails to start

Description: The installer doesn’t open or crashes immediately.

Symptoms:

• The installer window doesn’t appear.
• An error message appears, saying the installer has failed or stopped responding.

Troubleshooting:

• Ensure that you’re using an administrator account to run the installer.
• Check that there’s enough storage space available on your computer.
• Disable any antivirus software temporarily, as it may block the installer.
• Right-click the installer file and select “Run as Administrator.”
• Make sure you’ve downloaded the latest version compatible with your operating system.

VMware requires a reboot during installation

Description: The installer asks for a system reboot in the middle of installation.

Symptoms:

• You receive a message to restart the system to continue installation.
• The installation stops until a reboot occurs.

Troubleshooting:

• Restart your computer as prompted and try re-running the installer.
• Check if there are any pending Windows Updates, as these can cause VMware to request a reboot.
• Disable any non-essential startup programs temporarily to avoid conflicts.
• After rebooting, run the installer as Administrator to avoid repeat prompts.

VMware license key not accepted

Description: VMware doesn’t accept a license key during or after installation.

Symptoms:

• A message appears saying the license key is invalid or expired.

Troubleshooting:

• Double-check that you’re entering the key correctly, as it’s case-sensitive.
• Confirm that the key matches the version of VMware you’re installing.
• Ensure that you’re connected to the internet for online verification.
• Contact VMware support if the issue persists.

Network adapter not detected

Description: VMware can’t detect the network adapter on the host system.

Symptoms:

• The virtual machine has no internet or network connectivity.
• VMware displays an error that the network adapter isn’t detected.

Troubleshooting:

• Go to the virtual machine settings and check if the network adapter is enabled.
• Set the network adapter to “Bridged” mode or “NAT” mode to connect to the internet.
• Update your host’s network adapter drivers, as outdated drivers can cause issues.
• Restart the VMware services by going to “Services” on your host and restarting all the VMware-related services.

Incompatible OS detected during installation

Description: The installer reports that the OS is not compatible with VMware.

Symptoms:

• A message appears saying that your operating system is incompatible.
• The installation process halts without proceeding further.

Troubleshooting:

• Verify that your OS meets the minimum requirements for the VMware version you’re installing.
• Check VMware’s documentation for the specific version to see supported OS lists.
• If your OS is unsupported by newer versions, try installing an older version.
• If possible, consider updating your OS to one that’s compatible.

Virtual machine related issues

Next, let’s explore some VM-specific issues that you may encounter.

VM performance issues

Description: The VM runs slowly or doesn’t perform as expected.

Symptoms:

• VM lags or freezes during operation.
• High CPU or memory usage in the VM.

Troubleshooting:

• Increase the CPU and memory allocated to the VM in its settings, if possible.
• Reduce the number of background processes running within the VM’s OS.
• Adjust VMware’s priority settings on the host machine to allocate more resources to the VM.
• Defragment the VM’s virtual hard disk to improve data access speeds.
• Ensure that your host system has enough available resources to support the VM’s needs.

Snapshot problems

Description: Errors or problems occur when creating, restoring, or deleting snapshots.

Symptoms:

• Snapshot creation or deletion fails with an error.
• Restored snapshots don’t return the VM to the expected state.

Troubleshooting:

• Check available storage on the host, as low disk space can prevent snapshot operations.
• Avoid creating too many snapshots, as this can impact performance and stability.
• Consolidate snapshots regularly to free up space and improve performance.
• If a snapshot won’t delete, try restarting VMware services or reboot the host system and retry.

Compatibility issues with software or hardware

Description: The VM doesn’t support certain software or hardware.

Symptoms:

• Specific software or hardware fails to run within the VM.
• Error messages related to unsupported features or drivers.

Troubleshooting:

• Update VMware Tools in the VM, as it may improve compatibility with certain programs.
• Make sure that the VM’s OS meets the software or hardware requirements.
• If using USB devices, enable the “USB Controller” option in VM settings and connect devices manually.
• For graphics-intensive programs, ensure 3D acceleration is enabled and allocate enough video memory to the VM.

Cloning issues

Description: Problems arise when trying to clone a VM.

Symptoms:

• Errors occur during cloning.
• Cloned VM doesn’t start or has the same IP address as the original.

Troubleshooting:

• Verify that there’s enough storage available on the host for the cloned VM.
• Choose the “Customize” option during cloning to ensure that network settings don’t conflict between the original and clone.
• If the cloned VM has network issues, assign it a new IP address manually to avoid conflicts.
• Ensure that VMware Tools is up to date on the original VM, as this can help with cloning processes.

Host and infrastructure related issues

Issues in the host or the underlying virtualization infrastructure are also common. Let’s dissect some of them:

Storage-related problems

Description: The host runs low on storage or encounters issues with disk space allocation.

Symptoms:

• Errors when creating or expanding virtual disks.
• VM performance issues due to insufficient disk space.

Troubleshooting:

• Check the available storage on the host machine and free up space if it’s low.
• Use thin provisioning to save space — this allocates storage to VMs only as they need it.
• Set up disk space monitoring on the host to get alerts before space runs out.
• Increase the virtual disk size for VMs if they’re running out of storage by expanding the virtual disk in VMware’s settings.

Connectivity problems

Description: The host or VM has trouble connecting to the network or internet.

Symptoms:

• VMs can’t access the internet or communicate with other VMs or devices.
• The host network connection shows limited or no connectivity.

Troubleshooting:

• Verify the network settings in VMware. For example, check that the network adapter is connected and set to either “Bridged” or “NAT” mode.
• Restart network-related services on the host, or disconnect and reconnect the VM’s network adapter.
• If using Bridged mode, make sure that the host’s firewall isn’t blocking the connection.
• Ensure that the host’s network adapter drivers are up to date, as outdated drivers can impact connectivity.
• If using VLANs or specific network configurations, confirm that they’re properly set up in both the host and VM network settings.

Host CPU or memory overload

Description: The host’s CPU or memory usage is so high that it’s affecting VM performance.

Symptoms:

• High CPU or memory usage warnings on the host.
• VMs or the host system runs slowly or crashes frequently.

Troubleshooting:

• Reduce the number of VMs running simultaneously if the host has limited resources.
• Allocate resources efficiently by adjusting the CPU and memory settings for each VM.
• Check for unnecessary background processes on the host and terminate them to free up resources.
• Upgrade the host’s hardware if possible. For example, you may add more RAM or a better CPU for improved performance.
• Use a dedicated VMware monitoring tool to keep track of CPU and memory usage and adjust as needed.

Unexpected shutdowns or power issues in the host

Description: The host experiences unexpected shutdowns or power issues.

Symptoms:

• VMs shut down unexpectedly or fail to boot after a power loss.
• Error messages about data loss or corrupted files appear on reboot.

Troubleshooting:

• Connect the host to a reliable power source, ideally with an uninterruptible power supply (UPS) to handle power surges or outages.
• Set up VMware’s auto-recovery options to restart VMs automatically if the host reboots.
• Regularly back up VM data and snapshots to avoid data loss during sudden shutdowns.
• Check the host’s power management settings and set it to “High Performance” mode to reduce sleep or shutdown triggers.
• If shutdowns continue, inspect the host’s hardware, as power supply or overheating issues could be affecting stability.

Networking related issues

Next, this section covers networking related issues that users can encounter when working with VMware.

DHCP service not starting

Description: The VMware DHCP service fails to start.

Symptoms:

• VMs can’t obtain IP addresses automatically.

Troubleshooting:

• Open the Services panel on the host and check if “VMware DHCP Service” is running. If not, start it manually.
• Ensure that VMware Network Adapter settings for the VM are configured to use “NAT” or “Host-Only” mode, as these rely on DHCP.
• Restart VMware and the host machine to reset network services.
• Check if other DHCP services on the host or network are causing conflicts, and disable them if needed.
• Reinstall VMware Tools within the VM, as this can help restore network settings.

NAT not working

Description: Network Address Translation (NAT) fails.

Symptoms:

• VMs configured to use NAT cannot connect to the internet.
• No IP address is assigned to VMs in NAT mode.

Troubleshooting:

• Go to VMware’s “Virtual Network Editor” and check that NAT is enabled on the correct network adapter.
• Restart the VMware NAT Service in the host’s Services panel.
• Verify that the VM’s network settings are set to “NAT” mode, and not “Bridged” or “Host-Only”.
• If you’re using a firewall or VPN on the host, make sure that it isn’t blocking NAT connections.
• Reboot the host machine to reset the network configurations, then check the VM’s connection.

Bridged network connection issues

Description: Bridged networking fails.

Symptoms:

• VMs in bridged mode can’t communicate with the host or other devices on the network.

Troubleshooting:

• In the “Virtual Network Editor”, set the bridged network adapter to “Automatic” to choose the correct network interface.
• Disable any secondary network adapters on the host that aren’t in use, as these can cause confusion in bridged mode.
• Check the host’s firewall or antivirus settings, which may block bridged network traffic.
• Restart the VMware Bridged Networking service on the host. You can do this from the Services panel.
• If the problem persists, switch the VM to NAT mode as a temporary workaround.

VM network packet loss

Description: VMs experience dropped packets or slow network performance.

Symptoms:

• Network speeds are slower in the VM than on the host.
• High packet loss rate during network tests.

Troubleshooting:

• Check the VM’s network adapter bandwidth limit in VMware settings. If it’s set to a low value, increase it.
• Update the network adapter drivers on both the host and VM, as outdated drivers can affect performance.
• Switch between “Bridged” and “NAT” network modes to see if one improves speed.
• If supported by your network setup, enable jumbo frames, as this could reduce packet loss.
• Temporarily disable any firewall or VPN on the host to check for conflicts.

VLAN misconfigurations

Description: Incorrect VLAN configuration is leading to network connectivity issues.

Symptoms:

• VMs cannot communicate with each other or with external networks.

Troubleshooting:

• Verify the VLAN configurations on vSwitches and virtual machine network adapters.
• Ensure correct VLAN configuration on physical switches.
• Install and configure VMware Tools to synchronize VLAN settings.

Best practices for seamless VMware management

To keep VMware running smoothly, and avoid several of the aforementioned issues from occurring in the first place, follow these best practices:

Keep VMware software up to date

Keep all components of the VMware environment — including hypervisors, virtual machines, and guest operating systems — up to date, so that you don’t miss out on any new features, performance improvements, and security fixes. Moreover, you should also update VMware Tools on each VM, as it improves compatibility.

Proactively monitor and manage all VMs

Use monitoring tools to track VM performance, storage, and resource usage. Set up alerts for critical metrics like high CPU usage or low storage space, so that you can take action before performance is affected. You can also implement automated health checks to help identify and fix common issues before they escalate.

Optimize resource allocation

Allocate CPU, memory, and storage resources based on each VM’s needs, and avoid over-committing resources on the host. Use memory overcommitment and CPU resource limits carefully to avoid performance bottlenecks on critical applications.

Manage snapshots carefully

Limit the number of snapshots per VM, as too many can consume storage and degrade performance. Take snapshots only when necessary, such as before system updates or major configuration changes, and delete them once they’re no longer needed.

Backup regularly and test restores

Schedule regular backups of all your VMs to avoid data loss in case of hardware failures or other issues. Moreover, periodically test VM backups to ascertain the reliability of your recovery process.

Implement security best practices

Use strong passwords and multi-factor authentication to protect access to VMware management interfaces. Apply network segmentation to separate VM traffic from regular network traffic for added security.

Use performance optimization techniques

Defragment virtual disks periodically to improve data access speeds and VM responsiveness. Enable VMware’s resource scheduling features to balance load across the host’s resources. Additionally, use thin provisioning to save storage space by allocating disk space only as needed by each VM.

Conclusion

VMware is a widely-used virtualization tool that helps organizations get more out of their computing resources by allowing multiple virtual machines to run on a single host. But like any complex software, VMware can come with its own set of challenges related to installation, configuration, and network management.

By taking a systematic approach to troubleshooting, as outlined in this guide, and following best practices, administrators can reduce downtime, improve performance, and keep their virtual environments running smoothly.