Diagnosing the vSphere Client when it fails to connect to an ESXi host or vCenter Server
search cancel

Diagnosing the vSphere Client when it fails to connect to an ESXi host or vCenter Server

book

Article ID: 308932

calendar_today

Updated On: 04-09-2025

Products

VMware vSphere ESXi

Issue/Introduction

This article provides steps to troubleshoot connectivity issues to an ESXi host from the vSphere Web Client.  The article aims to help troubleshoot the common causes of being unable to connect by verifying network connectivity, authentication and permissions.
  • vCenter Server cannot connect to the ESXi host.
  • Connecting vCenter Server to the ESXi host fails.
  • vSphere Client cannot connect to the ESXi host.
  • One or more of these errors is displayed:
    • Login failed
    • Login failed due to a bad username or password
    • Cannot complete due login due to an incorrect username or password
    • Timed out waiting for server response
    • Failed To Connect to host

Environment

VMware vSphere ESXi

Resolution

Validate that each troubleshooting step below is true for the virtual environment. Each step provides instructions or a link to a document. To eliminate possible causes and take corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution. Do not skip a step.

Note: When performing a corrective action in any of the following steps, attempt reconnecting to ESXi host with the vSphere Client.

  1. Confirm connection to the correct hostname or IP address for the vCenter Server. Connections fail because incorrect server information may make the problem seem more complex than it is. Correct any incorrect names and try connecting to vCenter Server with the vSphere Client. If the connection fails using the hostname but succeeds with IP address, then it is probably a DNS error that needs to be corrected.  Check both forward and reverse DNS zones.

  2. Verify that network connectivity exists from the client workstation to the ESXi host. 
  3. Verify that the ESXi Server Management service on the ESXi host is running. For more information, see Restarting the Management agents on an ESXi or ESX host.

  4. Verify connectivity from the vCenter Server to the ESXi host on port 902. By default, ESXi listens on port 902 and therefore if the previous steps are all correct it most means that a physical firewall is blocking connectivity on port 902. For more information, see Testing port connectivity with Telnet.

  5. Verify the correct username and password are being used. Often, an incorrect username or password has been specified causing the log on failure to occur with the error: Cannot complete login due to an incorrect user name or password.

  6. Verify that the configured permissions for the account are sufficient to allow logging in to the ESX/ESXi host. For more information, see Troubleshooting permissions errors when connecting to an ESX/ESXi host with the vSphere/Virtual Infrastructure client.

Additional Information

Powered by Wolken Software