Thanks, I finally found the root cause.
in the old CWP installation /root/.my.cnf file looked like
[client]
user=root
password='password'
I have compared with a fresh installation and it looks like:
[client]
password=password
user=root
I removed the ' ' symbols from the password and it started to work perfectly well.
Note: nevertheless CWP was auto-updated the my.cnf file remained old
Hope it will help someone because it caused may other related issues including cron fails.
I also prevented New backup page to show up (it was completely blank)...
Issue resolved, thanks.