Windows: Zabbix agent is not available - Zabbix 7.2.9

[TeeJay13]

We recently upgraded to Zabbix 7.2.9 and have started experiencing frequent alerts indicating that the Zabbix Agent is terminating itself. Previously, we were on version 7.2.7 and encountered the "Windows: Zabbix agent is not available" alert only occasionally.

This is a POC server as we evaluate moving away from SolarWinds—a transition that looks promising. However, the frequent random stops of the agents are becoming increasingly frustrating. It is making me believe this is something happening with the Zabbix server itself instead of the agent causing this issue. When I go to the eventviewer > Systems > I do see errors when it terminates itself it says "The Zabbix Agent 2 service terminated unexpectedly. It has done this 1 time(s)."

I’ve come across threads where no definitive solution was provided, only a workaround:

1. Open Services on the affected server.
2. Locate and open the Zabbix Agent 2 service.
3. Navigate to the Recovery tab.
4. Change "First Failure" from Take no action to Restart the Service.

While this workaround may help, we have approximately 250 servers running Zabbix Agent 2, which makes implementing it manually quite impractical.

Here are the current setup details:

• Zabbix Agent 2 on all servers: 7.2.4
• Zabbix Server: 7.2.9 (Ubuntu)
• Database: MySQL (running on the same Ubuntu server)

Let me know if i'm missing anything or if you guys have any ideas that could lead me to solving this problem.

[Markku]

Right, they still have problems publishing signed packages for Windows for later versions. Watch https://support.zabbix.com/browse/ZBX-26464 for any progress on that (or just visit the Get Zabbix link later).

Since the last things in the logs mention the Exchange-related performance monitor items (which are quite rare in usual environments), you could also try disabling them.

I didn't say it earlier, but my Windows agents (in various versions of 4.x, 5.x, 6.x, 7.x) have years worked just fine without unexpected service problems. I do use the performance monitor items with DHCP servers for example.

Markku

[Markku]

What does the log file of Zabbix agent say about these events? It is usually near where the agent is installed.

Markku

[TeeJay13]

I'm going to have to enable DebugLevel again, I thought I had it on but I guess I uninstalled the Agent and it lost all the configs I had. Checking the log file currently there is nothing during that time frame just skips past it

[Markku]

Have you tried with the latest agent? I'd also recommend LTS versions (currently 7.0.x) for production due to the longer support, unless some specific new feature is absolutely needed.

Markku

[TeeJay13]

Have you tried with the latest agent? I'd also recommend LTS versions (currently 7.0.x) for production due to the longer support, unless some specific new feature is absolutely needed.

Markku

A few servers I put 7.2.6 as the agent but as of last night at 12:51 am the agent failed that was running 7.2.6. The logs stop at 12:47 AM

2025/06/24 00:47:25.386271 Calling C function "tls_new_server()"
2025/06/24 00:47:25.386271 Calling C function "tls_free()"
2025/06/24 00:47:25.386271 Calling C function "tls_ready()"
2025/06/24 00:47:25.386271 Calling C function "tls_send()"
2025/06/24 00:47:25.386885 Calling C function "tls_connected()"
2025/06/24 00:47:25.386885 Calling C function "tls_accept()"
2025/06/24 00:47:25.386885 Calling C function "tls_recv()"
2025/06/24 00:47:25.386885 Calling C function "tls_send()"
2025/06/24 00:47:25.386885 Calling C function "tls_accept()"
2025/06/24 00:47:25.387420 executed direct exporter task for key 'service.info[[MSExchangeDiagnostics state]]'
2025/06/24 00:47:25.387420 Calling C function "tls_recv()"
2025/06/24 00:47:25.387992 Calling C function "tls_recv()"
2025/06/24 00:47:25.387992 sending passive check response: '{"version":"7.2.6","variant":2,"data":[{"value":"0"}]}' to '(IP of Zabbix Server)'
2025/06/24 00:47:25.387992 Calling C function "tls_send()"
2025/06/24 00:47:25.388604 Calling C function "tls_accept()"
2025/06/24 00:47:25.388604 Calling C function "tls_connected()"
2025/06/24 00:47:25.388604 Calling C function "tls_write()"
2025/06/24 00:47:25.389153 Calling C function "tls_recv()"
2025/06/24 00:47:25.389153 Calling C function "tls_recv()"
2025/06/24 00:47:25.389153 Calling C function "tls_recv()"
2025/06/24 00:47:25.389708 Calling C function "tls_description()"
2025/06/24 00:47:25.389708 Calling C function "free()"
2025/06/24 00:47:25.389708 connection established using TLSv1.3 TLS_CHACHA20_POLY1305_SHA256
2025/06/24 00:47:25.389708 Calling C function "free()"
2025/06/24 00:47:25.390245 Calling C function "free()"
2025/06/24 00:47:25.390245 Calling C function "tls_connected()"
2025/06/24 00:47:25.390245 Calling C function "tls_recv()"
2025/06/24 00:47:25.390245 parsed performance counter \MSExchangeTransport Queues\Messages Queued for Delivery Per Second
2025/06/24 00:47:25.390245 executed direct exporter task for key 'perf_counter[[\MSExchangeTransport Queues(_total)\Messages Queued for Delivery Per Second]]'
2025/06/24 00:47:25.390785 [WindowsPerfMon] collected performance counters data
2025/06/24 00:47:25.390785 Calling C function "tls_read()"
2025/06/24 00:47:25.390785 Calling C function "tls_close()"
2025/06/24 00:47:25.391318 Calling C function "tls_recv()"

[Markku]

Right, they still have problems publishing signed packages for Windows for later versions. Watch https://support.zabbix.com/browse/ZBX-26464 for any progress on that (or just visit the Get Zabbix link later).

Since the last things in the logs mention the Exchange-related performance monitor items (which are quite rare in usual environments), you could also try disabling them.

I didn't say it earlier, but my Windows agents (in various versions of 4.x, 5.x, 6.x, 7.x) have years worked just fine without unexpected service problems. I do use the performance monitor items with DHCP servers for example.

Markku

[TeeJay13]

Right, they still have problems publishing signed packages for Windows for later versions. Watch https://support.zabbix.com/browse/ZBX-26464 for any progress on that (or just visit the Get Zabbix link later).

Since the last things in the logs mention the Exchange-related performance monitor items (which are quite rare in usual environments), you could also try disabling them.

I didn't say it earlier, but my Windows agents (in various versions of 4.x, 5.x, 6.x, 7.x) have years worked just fine without unexpected service problems. I do use the performance monitor items with DHCP servers for example.

Markku

Thanks for the insight, Markku. We changed everything to Active, which stopped the queue. We’ve still seen the Zabbix agent stop occasionally, but we configured the Zabbix service to automatically restart if it does.
Also moved to 7.4.0

[gregorywest]

I'm confused. I go to Service -> Services I get a completely empty list.

I am having the same issue with unable to connect to the agent.

Any hints?

Greg