Virtual machine users and vCenter Server administrators must use the vSphere Client 4.1 to connect to vCenter Server 4.1 or to connect directly to ESX 4.1 hosts.

The VI Client 2.5 and the vSphere Client 4.0 can be installed on the same machine.

The vSphere Client upgrade operation requires no downtime. No virtual machines or clients need to be powered off for this process.


(Optional) Use Add/Remove Programs from the Windows Control Panel to remove any previous vCenter Server client.

Older vCenter Server clients do not need to be removed and are useful if you need to connect to legacy hosts.


Install the vSphere Client 4.1.

After you install the vSphere Client 4.1, you can connect to vCenter Server using the domain name or IP address of the Windows machine on which vCenter Server is installed and the user name and password of a user on that machine.

If you do not have the VI Client 2.5 installed and you use vSphere Client to connect to VirtualCenter 2.5, the vSphere Client prompts you to download and install the VI Client 2.5. After you install the VI Client 2.5, you can use the vSphere Client log-in interface to connect to VirtualCenter 2.5 or vCenter Server 4.1.

Use the vSphere Client to connect to the vCenter Server IP address with your Windows login username and password. Specifically, use the login credentials appropriate to the Windows machine on which vCenter Server is installed. The vCenter Server username and password might be different than the username and password you use for ESX/ESXi.

If the vSphere Client displays security alerts and exceptions when you log in or perform some operations, such as opening performance charts or viewing the Summary tab, this might mean that your Internet Explorer (IE) security settings are set to High. If your IE security settings are set to High, enable the Allow scripting of Internet Explorer web browser control setting in IE.

If you cannot connect to the vCenter Server system, you might need to start the VMware VirtualCenter Server service manually. To start the service, in the Settings menu, select Control Panel > Administrative Tools > Services > VMware VirtualCenter Server. The machine might require several minutes to start the service.