vSphere Client fails to connect to vCenter Server 5

After upgrading a vSphere vCenter appliance to v5.1 Update 2 we found the the vSphere client installed on a Windows XP or Windows Server 2003 host machine would fail to connect to the vCenter Server 5.1 due to an unknown error.

vSphere Client could not connect to {vcenter_server}.

An unknown connection error occurred.  (The request failed because of a connection failure. (Unable to connect to remote server)).

VMware posted a technote for vCenter 5.5 regarding the SSL connection that appears to also work with the vCenter 5.1 Update 2 

For the vCenter Server Appliance

1. Connect to the vCenter Server Appliance via SSH. For more information, see Enable or Disable SSH Administrator Login on the VMware vCenter Server Appliance in the vCenter Server and Host Management Guide.
2. Navigate to the directory:
   
   /etc/vmware-vpx/
   
3. Backup the vpxd.cfgfile. Do not skip this step.
4. Open vpxd.cfgfile in a plan text editor
5. Add the <cipherList>ALL</cipherList> parameter between the <ssl>...</ssl> section of the configuration file, For example:
   
   <config>
   ...
   <vmacore>
   ...
   <ssl>
   ...
   <cipherList>ALL</cipherList>
   ...
   </ssl>
   ...
   </vmacore>
   ...
   </config>
   
   
6. Save and close the vpxd.cfgfile.
7. Restart the vCenter Server service for the change to take effect.

We hope that this information is helpful. Please let us know how this has helped you or if you have additional questions. As always Firestone Technical Resources, Inc. is here to help with your computer support issues - "Providing personal service for your impersonal technology."