This thread was brought to my attention - https://supportforums.cisco.com/thread/2246189

After updating Java to Update 45 - you can no longer login to UCSM (UCS Manager)

You may see one of two errors:

Login Error: java.io.IOException: Invalid Http response

Login Error: java.io.IOException: Server returned HTTP response code: 400 for URL: http://x.x.x.x:443/nuova

Cisco Bug ID: CSCuj84421

This is due to a change introduced in Java

The solution posted is to rollback to Update 25. Rolling back to Update 40 also works.