Troubleshooting an ESXi host in a "not responding" state

Products

VMware vCenter Server VMware vSphere ESXi

Issue/Introduction

This article provides steps to troubleshoot when an ESXi is in disconnected or a not responding state in vCenter Server. In addition, it provides steps to help you eliminate common causes for your problem by verifying that the configuration of your networking and management server agents is correct and confirm the availability of resources on your ESXi host.

Symptoms:

An ESXi host shows as "not responding" in vCenter Server.
An ESXi host shows as disconnected in vCenter Server.
Cannot connect an ESXi host to vCenter Server.
Virtual machines on an ESXi host show as greyed out in vCenter Server.
When attempting to add an ESXi to vCenter Server, you see an error similar to:

Unable to access the specified host, either it doesn't exist, the server software is not responding, or there is a network problem
In the vpxd.log file, you see entries similar to:
- <YYYY-MM-DD>T<time>.696-05:00 [08128 info 'vpxdvpxdMoHost' opID=37D08048-00006071-85] [HostMo] host connection state changed to [DISCONNECTED] for host-26725
  
  </time>
- <YYYY-MM-DD>T<time>.508-04:00 [04944 error 'vpxdvpxdInvtHostCnx' opID=HB-host-385@3560-79f8b53e] [VpxdInvtHostSyncHostLRO] FixNotRespondingHost failed for host host-385, marking host as notResponding
  <YYYY-MM-DD>T<time>.633-04:00 [00812 error 'vpxdvpxdInvtHostCnx' opID=HB-host-385@3565-12c9cfec] [VpxdInvtHostSyncHostLRO] FixNotRespondingHost failed for host host-385, marking host as notResponding
  
  </time></time>
  For more information, see Location of vCenter Server log files (1021804)
  
  Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.

Environment

VMware vSphere ESXi 6.x

VMware vSphere ESXi 7.x

VMware vSphere ESXi 8.x

VMware vCenter Server 6.x

VMware vCenter Server 7.x

VMware vCenter Server 8.x

Resolution

Important: Before proceeding, ensure to familiarize yourself with KB Article Understanding the difference between "Not Responding" and "Disconnected" ESXi hosts in VMware vCenter Server (2121031).

As there are a number of reasons why the ESXi host reaches a “Not Responding” state, VMware strongly recommends to:

Validate each troubleshooting step below is true for your environment.
Each step provides instructions or a link to another Knowledge Base article to eliminate possible causes. You can take corrective action as necessary.

Note: The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution. After each step is completed, try to reconnect the ESXi host back to vCenter Server. Please do not skip a step.

VMware ESXi host that is in a "Not Responding" state

ESXi

Verify that the ESXi host is accessible from vCenter server or vSphere Client.For more information, see ESX/ESXi hosts do not respond and is grayed out (1019082)
Verify that the ESXi host can be reconnected, or if reconnecting the ESXi host resolves the issue. For more information, see Changing an ESXi or ESX host's connection status in vCenter Server (1003480).
Verify that the ESXi host is able to respond back to vCenter Server at the correct IP address. If vCenter Server does not receive heartbeats from the ESXi host, it goes into a not responding state. To verify if the correct managed IP Address is set, see Verifying the vCenter Server Managed IP Address (1008030) and See also, ESXi host disconnects from vCenter Server after adding or connecting it to the inventory (2040630) and ESXi host keeps disconnecting and reconnecting when heartbeats are not received by vCenter Server (1005757).
Verify that network connectivity exists from vCenter Server to the ESXi host with the IP and FQDN. For more information, see Testing network connectivity with the ping command (1003486).
Verify that you can connect from vCenter Server to the ESXi host on TCP/UDP port 902. For more information, see Testing port connectivity with Telnet (1003487).
Verify if restarting the ESXi Management Agents resolves the issue. For more information, see Restarting the Management agents on an ESXi host (1003490).
Verify if the hostd process has stopped responding on the affected ESXi host. For more information, see Troubleshooting vmware-hostd service if it fails or stops responding on an ESX/ESXi host (1002849) See also : ESXi host is non-responsive and disconnected in ESXi 6.x (56450)
The vpxa agent has stopped responding on the affected ESXi host. For more information, see Troubleshooting the vCenter Server Agent when it does not start (1006128)
Verify if the ESXi host has experienced a Purple Diagnostic Screen. For more information, see Interpreting an ESX/ESXi host purple diagnostic screen (1004250)
ESXi hosts can disconnect from vCenter Server due to underlying storage issues. For more information, see Identifying Fibre Channel, iSCSI, and NFS storage issues on ESXi/ESX hosts (1003659).

Additional Information

Troubleshooting an ESXi host in a "not responding" state
For additional information, see All ESX hosts simultaneously show a status of Not Responding in vCenter (1011878).
Virtual machines appear as invalid or orphaned in vCenter Server

Troubleshooting vmware-hostd service if it fails or stops responding on an ESX/ESXi host
Changing an ESXi or ESX host's connection status in vCenter Server
Testing network connectivity with the ping command
Testing port connectivity with Telnet
Restarting the Management agents in ESXi
Verifying that the vCenter Server Agent Service is running on an ESX host
Checking for resource starvation of the ESX Service Console
Identifying Fibre Channel, iSCSI, and NFS storage issues on ESX/ESXi hosts
Collecting diagnostic information in a VMware Virtual Infrastructure Environment
Interpreting an ESX/ESXi host purple diagnostic screen
ESXi host disconnects intermittently from vCenter Server
Troubleshooting the vCenter Server Agent when it does not start
Determining if the xinetd service is running on an ESX host
Verifying the VMware vCenter Server Managed IP Address
All ESX hosts simultaneously show a status of Not Responding in vCenter Server
TCP and UDP Ports required to access VMware vCenter Server, VMware ESXi and ESX hosts, and other network components
Determining why an ESXi/ESX host was powered off or restarted
ESXi 5.0 hosts are marked as Not Responding 60 seconds after being added to vCenter Server
ESXi/ESX host disconnects from vCenter Server after adding or connecting it to the inventory

Impact/Risks:
Refer to each section to understand the impact and risks for those relevant actions.