There are a lot of reasons you can get that error. Best to go to VMware (kb.vmware.com) and do a search. You'll have lots of hits and just need to go through and try some fixes. I usually first try a different remote desktop and connect to the vCenter or sometimes the host directly.
If I connect to host with vsphere client still get error.
Have been searching VMware's kb's tks
Yeah it’s a generic error so troubleshooting is a real pain. Again if you can try a bunch of different hosts from which to connect– like a VM running on the same ESXi host.
If i vmotion to another host it works for a little while.
Just found root is full on host.
~ # vdf -h | tail -6
Ramdisk Size Used Available Use% Mounted on
root 32M 32M 0B 100% --
etc 28M 296K 27M 1% --
tmp 192M 4K 191M 0% --
hostdstats 1053M 15M 1037M 1% --
snmptraps 1M 0B 1M 0% --