vSphere Authentication Error – Best Tips and Solutions in 2025

A vCenter single sign-on service error occurred

vSphere is a powerful virtualization platform developed by VMware that allows users to efficiently manage and deploy virtual machines in their data center environments. However, like any complex software application, users may encounter authentication errors during the login process. When an error occurs during authentication in vSphere, it can be frustrating and disruptive. In this article, we will explore some common causes of authentication errors in vSphere and provide detailed solutions to troubleshoot and resolve them.

An architecture for exchanging security tokens and acting as an authentication broker is vCenter Single Sign-On (SSO). A SAML token is given to the user upon successful vCenter SSO authentication, enabling them to access vCenter services and carry out operations in accordance with their credentials. All communications are encrypted; only authenticated users can execute actions within their granted permissions. If you have any other problem like Cannot Download Files from vSphere Update Manager Patch Store. then read our article(Click Here)

The ‘an error occurred during vSphere authentication’ problem can be fixed by making sure:

• The server URL is correct.
• The URL is in FQDN format.
• The hostname is a trusted service provider alias.

Next, I will focus on this issue and offer detailed steps to add a short name access to vCenter in this article.

Fix: An error occurred during authentication VMware vSphere 7.0 enforces FQDN or IP address reverse resolution to FQDN to allow authentication for Single-signing. To enable short name access to vCenter, add the desired short name in the webclient.properties file.

Note: Ensure you have a vCenter Server Appliance (vcsa) backup before making any changes.

1. Use an SSH/PuTTY session to log in as root to the vCenter Server and enable shell

2. Stop the vSphere client service using the below command

• service-control –stop vsphere-ui

3. To personalise webclient.properties, go to the vsphere-ui location.

• cd /etc/vmware/vsphere-ui/

4. Use the command below to create a backup of webclient.properties before editing:

• cp webclient.properties /var/tmp/webclient.properties.bak

5. Add the desired shortname under the sso.serviceprovider.alias.whitelist

• vi webclient.properties
• Type i to enter insert mode
• Put the short name here (if there are several values, separate them with a comma).
• Press Esc to end insert mode, then wq to save and close the VI editor.

Example: sso.serviceprovider.alias.whitelist=vcsa70

6. Start the vSphere client service. service-control –start vsphere-ui

And there may be some other reasons besides this in vSphere Authentication Error.

Check your username and password:

The first step in troubleshooting an authentication error in vSphere is to verify that you are entering the correct username and password. Oftentimes, the simplest explanation is that the user has mistyped their credentials. Check for any typos, extra spaces, or whether the caps lock key is accidentally enabled. Passwords are case-sensitive, so ensure that the correct capitalization is used. If you are still unable to login, consider resetting your password for a fresh start.

Verify network connectivity:

Another common cause of vSphere authentication errors in vSphere can be related to network connectivity issues. Ensure that your network connection is stable and functioning properly. Check if there are any network outages or disruptions that could be impacting your ability to authenticate. Test your network connection by pinging the vSphere server or accessing other network resources. A strong and reliable network connection is crucial for successful authentication in vSphere.

Reset the vSphere password:

If you are unable to login to vSphere with your current password, it may be necessary to reset your password. Depending on your organization’s policies, the process for resetting your password may vary. You can typically reset your password through the VMware console or website. Follow the instructions provided for resetting your password, and make sure to choose a secure password that meets the organization’s password requirements.

Restart the vSphere server:

Sometimes, a simple server restart can help resolve authentication errors in vSphere. Restarting the vSphere server can refresh the system and clear any temporary issues that may be causing authentication failures. Before restarting the server, make sure to save any unsaved work or shut down any critical applications running on the server. Once the server has restarted, attempt to login to vSphere again and see if the authentication error persists.

Check for account lockout:

In some cases, repeated failed login attempts can result in your account being temporarily locked out for security reasons. If you suspect that your account may be locked out, contact your system administrator for assistance. The administrator can unlock your account or provide guidance on the account lockout policy in place. To prevent account lockout in the future, ensure that you are entering the correct credentials and avoid multiple failed login attempts.

In conclusion

Authentication errors in vSphere can be frustrating, but with the right troubleshooting steps, you can quickly resolve them. By checking your username and password, verifying network connectivity, resetting your password, restarting the vSphere server, and checking for account lockout, you can effectively troubleshoot authentication errors in vSphere and regain access to your virtualization platform. Remember to follow best practices for password security and network connectivity to prevent future authentication issues.