Error: cannot send list of active checks to [x.x.x.x]: host [SAFLOK-PC] not found

[sicae]

So I'm getting this error on both my personal laptop and a remote server on which I've installed Zabbix.

I'm running Zabbix proxy v2.2.10 (rev 54806) on server side (Linux), Zabbix 2.4.4 (rev 52334) client side (Windows XP for on, Windows 7 the other).

I have several hosts configured on the web interface, all working correctly (all seen by the proxy). But for some reason the two clients I want to add now keep giving the same error: cannot send list of active checks to [x.x.x.x]: host [SAFLOK-PC] not found ([SIMBA-GO] for my laptop).

(Netbios) hostnames are identical in conf file, in windows system, and in zabbix web interface.

Any help? I really don't get what the problem is/could be.

[onallion]

Are you sure those are their actual host names in Zabbix, not just visible host names?

[sicae]

I am indeed.

Screenshot of host config for the offending hosts:

SAFLOK-PC:


SIMBA-GO:

[onallion]

Any errors in the Zabbix agent logs?

Also, are you actually trying to send active checks to these hosts? If not then it doesn't even matter really

[sicae]

Thanks for the replies.

From one of the agent logs:

2372:20170331:133153.303 no active checks on server [x.x.x.x:10051]: host [SIMBA-GO] not found
2372:20170331:133353.347 no active checks on server [x.x.x.x:10051]: host [SIMBA-GO] not found

From the proxy logs:

3874:20170331:133207.802 cannot send list of active checks to [x.x.x.x]: host [SAFLOK-PC] not found
3874:20170331:133348.854 cannot send list of active checks to [x.x.x.x]: host [SIMBA-GO] not found
3874:20170331:133407.823 cannot send list of active checks to [x.x.x.x]: host [SAFLOK-PC] not found

Am I making any mistakes here? Hostnames that both machines look for seem to match, IP addresses match as well (xx'd them out for security).

Thoughts?

[nobodysu]

But can you resolve these names from given machines?
Netbios is known to be extremely unreliable, maybe duplicate these names in hosts file?

[ktt]

Similar in Linux

I'm having same problems in Linux hosts. Both are running Ubuntu 16.04 LTS. Zabbix version is 3.2.8.

Here is snippet from server log:
--8<--8<--
25666:20180103:105053.617 cannot send list of active checks to "xx.xx.xx.xx": host [yyyy] not found
--8<--8<--

And here from zabbix agent log:
--8<--8<--
28106:20180103:105053.647 no active checks on server [yy.yy.yy.yy:10051]: host [yyyy] not found
--8<--8<--

Based on those logs, Zabbix agent can communicate with server, but for some reason, the server just can't find information for that host.

The host name (for the host with Zabbix agent) is written to the "host name" field exactly as it is defined on the host, and it is exactly as in the log.

[allexpetrov]

Hello ktt,

Please try to check the Zabbix Agent hostname by

 zabbix_get -s 127.0.0.1 -k agent.hostname

and compare it with the one you have on the Zabbix Server frontend page under the Host name(not the Visible name). Not that the hostname is case-sensitive. You could share the details with the community to be able to help you!


Regards,
Aleksejs!

[ebonweaver]

I'm seeing a similar issue. The server log lists 3 hosts that it's constantly failing to sent a list of active checks. It's failing because those hosts do not exist. Why is Zabbix trying to contact things that don't exist? The hosts in question were deleted long ago, but it seems something was left behind that Zabbix failed to clean up? There some kind of maintenance task that may clean out old junk? Similarly, the unreachable poller process is way too active considering there is no discovery configured anymore. It again appears something is stuck, but even a reboot won't clear these things...

[Alfista]

I have similar issue too: cannot send list of active checks to "127.0.0.1": host [Zabbix Server] not found

Can someone help to resolve it?
Thanks.

[Alfista]

The problem was in not coresponding names in configuration file and host name in front end (need to be the same with the same capitals).

[dsteinkopf]

I also had this problem. The solution for me was: When a server is monitored via proxy, then the server's agent has to be configured "ServerActive=my-proxy" because the main zabbix server does not expect to get values directly from this server.

[samarcos]

I am having the same issue,
what does the error mean?
cannot send list of active checks to "192.168.47.58": host [FRONTDESK] not found

I am getting this error on the Proxy logs, the proxy is my pfsense router running the Zabbix Proxy 5.2
I was thinking that the proxy was unable to connect to the workstation, but it does resolve correctly.

[Atsushi]

I think this is because the name FRONTDESK is specified for Hostname in the Zabbix agent configuration file, and the host with the same name is not registered in the Zabbix server side setting.

[samarcos]

Yea
I figured it out, the host name on zabbix server web interface has to be the same as the hostname in the zabbix agent config file, not the device hostname.
Also, since I was using a proxy, when you change the hostname on the zabbix server web gui, it takes time for the proxy to get the update usually 60 min.

[NE1Scott]

i have a similar error but a different config.

Using Zabbix server 5.0.13-1 and getting the same error but using this server to directly talk to each agent on the remote servers so proxy rules shouldn't apply.

I am only specifying the IP address to monitor and not the host name because we purposefully made our Zabbix "host name" more informative than the system name. (Prod_OANIS_UK2-O13-CZS1AOS where Prod_OANIS is not part of the machine's actual name)
I left the Visible name blank and the Agent IP Address is specified but not the DNS name.

For the most part I am using the Zabbix default Windows template but I think we tweaked the CPU monitor to show high activity for a 30 second period. Most are Win 2008R2 servers.

But I get countless errors in the zabbix_server.log file
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4424:20220105:225418.881 cannot send list of active checks to "xxx.xx.xx2.216": host [UK2-O13-CZS1AOS.hhu.local] not found
4421:20220105:225419.287 cannot send list of active checks to "xxx.xx.xx..133": host [UK-O13-DRS1] not found
4422:20220105:225419.417 cannot send list of active checks to "xxx.xx.xx..233": host [UK2-ZZI-VCS2.zzihosting.corp] not found
4421:20220105:225419.780 cannot send list of active checks to "xxx.xx.xx2..109": host [UK-O13-IWS4.hhu.local] not found
4423:20220105:225420.728 cannot send list of active checks to "xxx.xx.xx2.107": host [UK-O13-IWS3.hhu.local] not found

[cyber]

4424:20220105:225418.881 cannot send list of active checks to "xxx.xx.xx2.216": host [UK2-O13-CZS1AOS.hhu.local] not found

This means, that host with IP xxx.xx.xx2.216 comes and states: "Hello I am UK2-O13-CZS1AOS.hhu.local, please give me my active checks" and your server cannot find this host, because you have named it Prod_OANIS_UK2-O13-CZS1AOS.

Your hostname in agent config and in Zabbix have to match! It does not matter, that you communicate over IP and not DNS... If you want, then use visible name for displaying whatever name you need for this. Use smilies there or emoticons, if you wish, but use matching names in config file and hostname! It is the basics of configuring a host

Host name

Enter a unique host name. Alphanumerics, spaces, dots, dashes and underscores are allowed. However, leading and trailing spaces are disallowed. Note: With Zabbix agent running on the host you are configuring, the agent configuration file parameter Hostname must have the same value as the host name entered here. The name in the parameter is needed in the processing of active checks.

If you are worried about your informational hostnames in trigger names etc. then if you already have {HOST.NAME} there, it is referring to visible name. If visible name is empty, then it does fallback to host name ({HOST.HOST}).