The bug can also be reproduced on rhel7,so clone the bug to rhel7.
version:
libvirt-1.0.3-1.el7.x86_64

+++ This bug was initially created as a clone of Bug #819729 +++

Description of problem:
Unclear error message when connect vCenter server with virsh command "virsh -c esx://xxx.xxx.xxx.xxx/?no_verify=1", the error "internal error Could not find ComputeResource with name '(null)'" will be shown.

Version-Release number of selected component (if applicable):
# rpm -qa |grep libvirt
libvirt-client-0.9.10-16.el6.x86_64
libvirt-debuginfo-0.9.10-14.el6.x86_64
libvirt-0.9.10-16.el6.x86_64
libvirt-python-0.9.10-16.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.When connect ESXi server,pass the url of the Virtualcenter.

eg:virsh -c esx://<VirtualcenterIP>/?no_verify=1
Enter username for ip [root]:
Enter administrator's password for ip: 

  
Actual results:
[root@test ~]# virsh -c esx://10.66.6.123/?no_verify=1
Enter username for 10.66.6.123 [root]: administrator
Enter administrator's password for 10.66.6.123: 
error: internal error Could not find ComputeResource with name '(null)'
error: failed to connect to the hypervisor
[root@test ~]# 

Expected results:
There should be clear error messages given like:the host is neither an ESX 3.5, 4.x nor 5.x host

eg:# virsh -c esx://10.66.6.48/?no_verify=1
Enter username for 10.66.6.48 [root]: administrator
Enter administrator's password for 10.66.6.48:
error: internal error 10.66.6.48 is neither an ESX 3.5, 4.x nor 5.x host
error: failed to connect to the hypervisor

Additional info: