Ntopng package issue after upgrading to a new snapshot

[jjstecchino]

I am having an issue with ntopng on 2.3.3. After upgrading to a new snapshot ntopng does not restart. A manual restart fails.
I see this in the logs:

/rc.start_packages: The command '/usr/local/bin/redis-cli SET ntopng.user.admin.password 'f9f16d97c90d8c6f2cab37bb6d1f1992'' returned exit code '1', the output was 'Could not connect to Redis at 127.0.0.1:6379: Operation timed out Could not connect to Redis at 127.0.0.1:6379: Operation timed out'

Reinstalling ntopng fixes the problem until the next snapshot upgrade.