Nagios Support Forum

After the upgrade to 2026R1 we encounter the above ERROR: Invalid host address message when running a service check command on the localhost.
The localhost host definition is set to 127.0.0.1

"127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4"

It looks like the service is nog resolving correctly the "managed host". This works fine with other hosts not beeing localhost.

Set the check to use the address rather than localhost.
I'd also use the hostname rather than localhost.

I have also found other service checks that run into the ERROR other then localhost. So it looks like a parsing issue in the GUI part. The checks seem to run ok from CLI.

Set the other checks to use the address rather than the hostname.

The localhost definition is set to IP address, In a service definition you have to point to a "nagios" host.
Running the "run check command" from the CCM works fine for the HTTP and PING service. When ran they come up with the 127.0.0.1 field, other checks like the load are running into the ERROR.

Hi @CBoekhuis,

Thanks for reaching out.

Sounds like the CCM is giving you the correct results, for the service checks using localhost, but that is not what you are seeing on other pages. The image in your first post is not displaying for me, so I can't tell what plugin(s) are erroring or where in the GUI. Are you seeing this on any particular page or dashboard? If you could provide a list of some of the plugins that are erroring, that would be helpful.

You may want to post the text of a failing service and the associated command.

Hi @CBoekhuis,

Our support team tells me this is a known bug. When it is fixed, it will show up in our CHANGELOG as [GL:XI#2160].