While executing root.sh during a 19c Grid Infrastructure on a two RAC nodes I experienced this error:

2020/05/18 10:22:47 CLSRSC-594: Executing installation step 18 of 19: ‘ConfigNode’.
2020/05/18 10:22:59 Oracle Clusterware infrastructure error in CLSECHO (OS PID 27328): ADR home path /u01/oracle/diag/crs/clssrv1-vip2/crs does not exist; ADR initialization will try to create it
CLSRSC-594: Executing installation step 19 of 19: ‘PostConfig’.
PRKH-1010 : Unable to communicate with CRS services.
PRKH-3003 : An attempt to communicate with the CSS daemon failed
2020/05/18 10:23:31 CLSRSC-180: An error occurred while executing the command ‘srvctl start listener -l LISTENER’
Died at /u01/grid/12.2.0.3/crs/install/crsutils.pm line 12160. 

Analysis:

When checked Server static host name it wasn’t set properly:

 # cat /etc/hostname
localhost.localdomain

# hostnamectl | grep hostname
Static hostname: localhost.localdomain
Transient hostname: clssrv1-vip2

# hostnamectl –static
localhost.localdomain 

Fix:

Set the server static host name properly using this Linux command:

# hostnamectl set-hostname clssrv1

Now the static name is showing the correct value of server name:

# hostnamectl
   Static hostname: clssrv1         
         Icon name: computer-server
           Chassis: server
        Machine ID: r93o4kde7b4d8o333jr4406686a4e
           Boot ID: 6b34567b7a3577767a1e3768306d954
  Operating System: Oracle Linux Server 7.4
       CPE OS Name: cpe:/o:oracle:linux:7:4:server
            Kernel: Linux 4.1.12-94.3.9.el7uek.x86_64
      Architecture: x86-64

Now re-execute the root.sh script. If it fails again remove the Grid Infrastructure installation and re-install it again.