The NetBackup plug-in is not shown in the vSphere Client (HTML5) interface after vCenter upgrade from older versions to vCenter 7.0 or later
This issue occurs because older versions of vCenter try to re-deploy the plug-in installation media zip file already downloaded by the vCenter from previous registration, which is not compatible with vCenters of versions 7.0 or later.
To solve this issue, you must install the NetBackup plugin provided for newer versions of vCenter. This plugin package is available at this URL on primary server:
https://primary_server_host_name:8443/nbwebservice/plugins/netbackup-vwc-plugin-html5ui.zip
Note:
This example uses a port number of 8443. The port number on the primary server however may be different.
See Installing the NetBackup plug-in for vSphere Client (HTML5).