Error: The command name "list_plugins_on_server" is not a recognized command

When trying to check all plugins available on the server getting error:

[ora11g@monitorem ~]$ emcli list_plugins_on_server

Error: The command name "list_plugins_on_server" is not a recognized command.

Run the "help" command for a list of recognized commands.

You may also need to run the "sync" command to synchronize with the current OMS.

Cause:
emcli is not synchronized with OMS

Action:

[ora11g@monitorem ~]$ which emctl

/u01/HomeEM12c/12c_Home/oms/bin/emctl

[ora11g@monitorerp ~]$ emcli sync

Error: Session expired. Run emcli login to establish a session.

[ora11g@monitorerp ~]$ emcli login -username=sysman

Enter password


Login successful

[ora11g@monitorem ~]$ emcli sync

Synchronized successfully