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appveyour host agent "Error registering Host Agent: Object reference not set to an instance of an object."

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Jan Vesely

29 Dec, 2025 03:13 AM

Hi,

I've noticed that a host agent running in a local container stopped connecting as of few days ago.
Inspecting the logs, I found the following error:
Dec 28 22:20:07 07f9c5e67b2a appveyor-host-agent[23]: info: Appveyor.HostAgent.AppHost[0]
Dec 28 22:20:07 07f9c5e67b2a appveyor-host-agent[23]: Registering all clouds received from AppVeyor
Dec 28 22:20:07 07f9c5e67b2a appveyor-host-agent[23]: fail: Appveyor.HostAgent.AppHost[0]
Dec 28 22:20:07 07f9c5e67b2a appveyor-host-agent[23]: Error registering Host Agent: Object reference not set to an instance of an object.

the above is observed using:
ii appveyor-host-agent 7.0.3340 amd64 Appveyor Host Agent for Linux

but the older release available at https://www.appveyor.com/downloads/appveyor/appveyor-host-agent.deb (7.0.3212) has the same behaviour using ubuntu 20.04.

I've tried removing /var/opt/appveyor/host-agent/host-agent.db*, removing all registred clounds via web interface a re-connecting the host agent, but none of this helped.

1. Support Staff 1 Posted by Feodor Fitsner on 29 Dec, 2025 07:36 PM

   

   Try newer version I provided a link to in another post.

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2. 2 Posted by Jan Vesely on 30 Dec, 2025 10:09 PM

   

   I can still see the issue running 7.0.3340:

   root@07f9c5e67b2a:~# /opt/appveyor/host-agent/appveyor Version
   7.0.3340
   root@07f9c5e67b2a:~# journalctl -u appveyor-host-agent | tail
   Dec 30 22:04:01 07f9c5e67b2a appveyor-host-agent[1378]: fail: Appveyor.HostAgent.AppHost[0]
   Dec 30 22:04:01 07f9c5e67b2a appveyor-host-agent[1378]: Error registering Host Agent: Object reference not set to an instance of an object.
   Dec 30 22:04:01 07f9c5e67b2a appveyor-host-agent[1378]: info: Appveyor.HostAgent.AppHost[0]
   Dec 30 22:04:01 07f9c5e67b2a appveyor-host-agent[1378]: Checking Host Agent connection: XXXXXXXXXXXXX
   Dec 30 22:04:22 07f9c5e67b2a appveyor-host-agent[1378]: warn: Appveyor.HostAgent.AppHost[0]
   Dec 30 22:04:22 07f9c5e67b2a appveyor-host-agent[1378]: Ping callback has not received in 20 seconds: XXXXXXXXXXXXX
   Dec 30 22:04:22 07f9c5e67b2a appveyor-host-agent[1378]: warn: Appveyor.HostAgent.AppHost[0]
   Dec 30 22:04:22 07f9c5e67b2a appveyor-host-agent[1378]: Host Agent connection is not responding on AppVeyor events
   Dec 30 22:04:22 07f9c5e67b2a appveyor-host-agent[1378]: info: Appveyor.HostAgent.AppHost[0]
   Dec 30 22:04:22 07f9c5e67b2a appveyor-host-agent[1378]: Stopping Host Agent connection...

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3. Support Staff 3 Posted by Feodor Fitsner on 30 Dec, 2025 10:47 PM

   

   What OS are you running it on?

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4. 4 Posted by Jan Vesely on 31 Dec, 2025 01:03 AM

   

   The above is using Ubuntu "22.04.5 LTS (Jammy Jellyfish)"

   The problem originally appeared on Ubuntu 20.04 using 7.0.3212 (https://www.appveyor.com/downloads/appveyor/appveyor-host-agent.deb) around Dec 21. The same container that worked OK before was no longer able to connect.

   • Edit