After upgrade to 4.2, some clients stop reporting to server

[IteaAgain]

Hello,
i have a strange problem after updating zabbix server, proxy and agaent from 3.4 to 4.2.6
The problem only appears with one proxy and some clients.

The proxy's local agent data is displayed correctly in zabbix-server's GUI.
also the data from a long outdated client is displayed correctly (zabbix_agent 0.8.6 on a pfsense 2.2.6)
BUT, the data from 3 different VMs is not displayed at all, only two UserParameters of one host are displayed.

The funny is, with zabbix_get i can get ALL values (well, at least the ones i have tested) read from those VMs, from the Proxys cmdline.

It seems that even Proxy is not sending the data or the data is not displayed somehow.

In the log files of the missing VMs there is no error shown, instead it shows that it sends the values to the Proxy.

In the log of the Proxy i can see how it gets values from the agents. No error here.

In the log of the Server i see a lot of successfull trapper messages from the Proxy. If there are any messages coming from the missing VMs i just don't know.

Well, can anybody help me to solve this problem?
It seems that somehow between Proxy sending the values and displaying the values in zabbix server those values got lost.

I do not have any idea any more and i lost nearly a day now.... :-(

[dimir]

In 4.0 the value timestamp auto-correction was removed from Zabbix: https://www.zabbix.com/documentation...amp_correction
Since then we strongly advise users to use ntpd on all monitored hosts: https://www.zabbix.com/documentation...ynchronisation

[IteaAgain]

Yes, i have read that tip in the forum already. All VMs and servers got there time from the same Windows Domaincontroller. I have checked also manually, seems fitting (by eye).

However, how can i see/check what values from remote Zabbix-agents are send via Zabbix-Proxy to the Zabbix-server on the zabbix-server side?
That i can check if the values from the agents reach the server at all or get lost on the proxy?
I can see that data is coming to the server from proxy-host, but don't know if this includes the missing data or if this is only data from proxy itself or agent itself on the proxy-host.

I#m not sure if the problem is related to wrong config or somehow a database error and the data is just not written to database and therefore not displayed on gui?