Troubleshooting a virtual machine that is unable to power on
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Troubleshooting a virtual machine that is unable to power on

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Article ID: 343809

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

This article provides steps to assist in determining why a virtual machine (VM) cannot be started on an ESX/ESXi host.


Symptoms:

  • A virtual machine hosted on an ESX/ESXi host cannot be powered on
  • The virtual machine power on task fails
  • The virtual machine does not turn on



Environment

VMware vSphere ESXi

Cause

Causes:
There are multiple potential causes for not being able to power on VMs:

  • Problems with file locks
  • VM file corruption
  • VM snapshot problems
  • VM guest OS problems
  • VM configuration problems
  • ESXi OS problems
  • vCenter OS problems
  • Storage Array/Datastore problems
  • Network problems

Resolution

When a virtual machine fails to power on, a reason may be logged to the vmware.log file for the virtual machine, to the management agent logs, or presented in the client. Review any messages and consider these points:

  1. The virtual machine monitor may be asking a question to be answered during startup. A virtual machine may pause the power-on task at 95% to obtain additional information from the administrator. For more information, see Powering on a virtual machine pauses at 95% while waiting for a question to be answered (1027096).
     
  2. Creating a new power-on task may fail if another task for the virtual machine or other component is already in progress, and multiple concurrent tasks on the object are not permitted. For more information, see:
     
  3. The virtual machine may be configured to reserve physical memory on the host, but the host memory is over-committed and the required memory is unavailable. For more information, see:
     
  4. The virtual machine may be starting in a VMware High Availability cluster with strict admission control enabled, and there are insufficient resources to guarantee failover for all virtual machines. For more information, see:
     
  5. A file required for starting the virtual machine, such as a virtual disk or swap file, may be unavailable or missing. For more information, see Investigating virtual machine file locks in ESX/ESXi.
     
  6. The virtual machine may have been previously suspended and making use of CPU features which are unavailable or incompatible with the CPU features available on this host. The virtual machine cannot be started without the required features. For more information, see:
     
  7. The virtual machine may require another CPU feature which is unavailable on this host. The virtual machine may produce a message similar to msg.cpuid.<FeatureName>, identifying the specific feature it has been configured to require. Move the virtual machine back to the host which has the required CPU features, or edit the virtual machine's configuration to remove the requirement.
     
  8. The virtual machine may start, but quickly fail with an error during startup. Review the contents of the vmware.log file in the virtual machine's directory for any errors or warnings, and search the Knowledge Base for the error or warning. Base your troubleshooting on the specific messages seen in the logs. For more information, see:
     
  9. If the virtual machine does successfully power on, but the guest OS doesn't start correctly, there may be an incompatibility between the virtual hardware and drivers within the guest OS. For example, a missing SCSI driver may be required for booting. For more information, see Windows virtual machine configured to use a BusLogic SCSI controller reports that the operating system does not support the controller.
     
  10. If the guest OS, or a driver or application within the virtual machine experiences a problem during startup, the guest OS may become unresponsive. Continue troubleshooting. For more information, see Troubleshooting unresponsive guest operating system issues (1007818).

Additional Information

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