Here are classic case of issues and error that can be detected thanks to the Health Check command

Outdated or invalid licence key

If you are using a invalid or an outdated licence key, you will have ERRORS on the Licence key part. You will also have a At Risk level near the end of the key validity date.

localhost address on the daemon configuration

The installation is installing the default daemons with the localhost address. If you are setuping for a distributed setup, you MUST set the IP/FQDN address instead.

The mongodb database is stopped

If you see such errors messages:

ERROR: [Synchronizer] cannot connect to mongodb server: mongodb://localhost/?safe=false (could not connect to localhost:27017: [Errno 111] Connection refused)
ERROR: [webui::mongodb module /etc/shinken/modules/mongodb.cfg:5] cannot connect to mongodb server: mongodb://localhost/?safe=true (could not connect to localhost:27017: [Errno 111] Connection refused)

It means that the mongodb database is stopped. You an try to restart it with the command:

/etc/init.d/mongodb start

And if it stil fail, you can look at the mongodb database logs available in /var/log/mongodb/mongod.log

The Graphite servers are not available

If you see such errors:

ERROR: [webui::graphite backend] cannot request graphite server at 127.0.0.1 (<urlopen error [Errno 111] Connection refused>)

It means that the Graphite services are stopped.

You can try to restart them:

/etc/init.d/httpd start
/etc/init.d/carbon-cache start

One of your Shinken daemon is stopped:

If you see such an error:

ERROR: [/etc/shinken/synchronizers/synchronizer-master.cfg:13] cannot contact daemon (<urlopen error [Errno 111] Connection refused>)

It means that one of your Shinken daemons is stopped. You can try to restart it on its server:

 /etc/init.d/shinken start