By default, vSphere Web Client sessions terminate after 30 minutes of idle time, requiring the user to log in again to resume using the client. You can change the timeout value by editing the webclient.properties file. This file is located at the server where the webclient is installed, which is in my case the vCenter server.

Log on to the computer where the vSphere Web Client is installed and navigate to the the webclient.properties file:

• Windows 2003
  • %ALLUSERSPROFILE%Application Data\VMware\vSphere Web Client
• Windows 2008
  • %ALLUSERSPROFILE%\VMware\vSphere Web Client
  • Default: C:\ProgramData\VMware\vSphere Web Client
• vCenter Server Appliance
  • /var/lib/vmware/vsphere-client

Edit the file to include the line session.timeout = value where value is the timeout value in minutes.

Note that to set the client to never time out, specify a negative or 0 value for the timeout.

# Session timeout in minutes, default 120
session.timeout = 120

To activate the changes you'll have to restart the Web Client Service:

• On Windows operating systems, restart the VMware vSphere Web Client service
• On the vCenter Server Appliance, restart the vSphere-client service