B.2. The URI Failed to Connect to the Hypervisor

Several different errors can occur when connecting to the server (for example, when running virsh).

B.2.1. Cannot read CA certificate

Symptom
When running a command, the following error (or similar) appears: 
$ virsh -c name_of_uri list
error: Cannot read CA certificate '/etc/pki/CA/cacert.pem': No such file or directory
error: failed to connect to the hypervisor
Investigation
The error message is misleading about the actual cause. This error can be caused by a variety of factors, such as an incorrectly specified URI, or a connection that is not configured.
Solution
Incorrectly specified URI
When specifying qemu://system or qemu://session as a connection URI, virsh attempts to connect to host names system or session respectively. This is because virsh recognizes the text after the second forward slash as the host.
Use three forward slashes to connect to the local host. For example, specifying qemu:///system instructs virsh connect to the system instance of libvirtd on the local host.
When a host name is specified, the QEMU transport defaults to TLS. This results in certificates.
Connection is not configured
The URI is correct (for example, qemu[+tls]://server/system) but the certificates are not set up properly on your machine. For information on configuring TLS, see Setting up libvirt for TLS available from the libvirt website.