My VMware Infrastructure client simply refused to connect to my ESXi server today. The error:
"Error - Server could not interpret client request".
Took a while to figure it out, VMWare's site was not too helpful.
Here is how to re-establish connectivity with your server.
1. Log on to the ESXi physical server directly (if its in a different building, put on your walking shoes)
2. Navigate to the Option: Restart Management Agents
3. Restart the management agent (F11 to confirm)
4. Log in using the VMWare Infrastructure Client
Connectivity should now be established.