A day has arrived to upgrade our vCenter server from vCenter 5.0 to vCenter 5.1. During Off hours, Upgrade went smoothly and we were happy to leave for the day without any issues. Next day morning, Proudly logged into my new upgrade vCenter server and going through my inventory. I have searched one of the Virtual Machines from my vCenter inventory. Entered the virtual Machine name in the search bar and hit Enter to get the search results and i was shocked by the below error message

Error when trying to sort : Login to query service failed: The underlying connection was closed: An unexpected error occurred on a send. Authentication failed because the remote party has closed the transport stream

I understood that this error message is only occurred when tried connecting to my vCenter server using vSphere client  installed on Windows 2003 server but i am not getting above error when i perform inventory search in Windows 2008 and above server versions.

This issue occurs due to increased security of the cipher strengths used by the VMware Management Web Services components. This change was introduced in vSphere 5.1. Host operating system where you are trying to connect to these components should support a higher cipher strength.

In windows Vista and Windows Server 2008, the proper cipher strengths are built into the operating system itself but for older version of windows operating systems, A Microsoft hotfix must be applied to the system to support the required cipher strengths

Download the hotfix (KB948963) and install on the System(windows 2003) from where you want to connect to vCenter server using vSphere client. Thats it. Now you are free to search to inventory objects using your vCenter server inventory search

.I hope this post is informative for all. This post written by referring the VMware KB article 2031053 . Thanks for Reading !!!