BUG REPORT: Auto Upgrade Issus

[q2uantum]

Describe the bug
We have Auto Update enabled on SNclient, we have found in the last few versions that when the auto update runs, it doesnt start the snclient service once it has completed, which then means we have 100s of servers alerting on our Nagios boards, and we have to manually connect and restart the snclient service.

From the Log file it says that it has upgraded successfully BUT then when we restart the service manually it says its starting the previous version and not the new one.

[2025-11-19 04:59:17.494][Info][pid:5608][task_updates:286] [update] update successful from v0.38 to v0.39, restarting into new version
[2025-11-19 04:59:17.495][Info][pid:5608][listener:309] stopping nrpe listener on :5666
[2025-11-19 04:59:17.594][Info][pid:5608][winservice:25] snclient exited (pid:5608)
[2025-11-19 08:58:53.238][Info][pid:7612][snclient:254] SNClient starting (version:v0.38. - build:d4ae5b6 - host:IH-STRON-SQL-P1 - pid:7612 - os:Microsoft Windows Server 2022 Standard 21H2 - arch:amd64 - go1.24.6 - user:STRON\IH-STRON-SQL-P1$)
[2025-11-19 08:58:53.330][Info][pid:7612][listener:246] starting nrpe listener on :5666

File properties confirm we are still on 0.38.

To Reproduce
Steps to reproduce the behavior:

1. Enable Auto Upgrade
2. Let it upgrade
3. Service doesnt get started

Expected behavior
Autoupgrade completes and then restarts the service.

Software (please complete the following information):

• OS - Windows 2019 / Windows 2022
• Architecture amd64
• SNClient Version - v0.38 / 0.39 upgrade

Additional context
Add any other context about the problem here.

[sni]

could you increase the log level? I just tried, and it worked as expected here.

[2025-11-19 11:45:06.012][Info][pid:7804][snclient:254] SNClient starting (version:v0.38. - build:d4ae5b6 - host:VM - pid:7804 - os:Microsoft Windows 11 Pro 25H2 - arch:arm64 - go1.24.6 - user:...)
[2025-11-19 11:45:06.034][Info][pid:7804][listener:246] starting prometheus listener on :8443
[2025-11-19 11:45:06.034][Info][pid:7804][listener:246] starting https listener on :8443
[2025-11-19 11:45:06.034][Info][pid:7804][listener:246] starting windowsexporter listener on :8443
[2025-11-19 11:45:50.519][Info][pid:7804][task_updates:286] [update] update successful from v0.38 to v0.39, restarting into new version
[2025-11-19 11:45:51.029][Info][pid:8504][snclient:254] SNClient starting (version:v0.39. - build:77b69ef - host:VM - pid:8504 - os:Microsoft Windows 11 Pro 25H2 - arch:arm64 - go1.24.9 - user:...)

[q2uantum]

@sni We are just going to do this on a test server and see if it fails or goes through. From what my team are telling me it doesnt fail on every server, this morning we had around 40 servers that this failed on, although we know that some servers did upgrade ok.

Once we see the update has happened on the test server I will post the log file.

[q2uantum]

@sni We turned logging up on a server that failed last week, and it tried again on the 20/11.

I have attached the log from the upgrade, which you can see at the end that it stopped the service and never restarted it.

When we manually restarted the service this is what we got in the log file:

[2025-11-20 08:17:26.474][Trace][pid:19364][snclient:211] os args: []string{"C:\Program Files\snclient\snclient.exe", "winservice"}

[2025-11-20 08:17:26.516][Info][pid:19364][snclient:254] SNClient starting (version:v0.38. - build:d4ae5b6 - host:xxxxxxxxxx - pid:19364 - os:Microsoft Windows Server 2022 Standard 21H2 - arch:amd64 - go1.24.6 - user:xxxx\xxxxxxxxxxx$)

[2025-11-20 08:17:26.545][Debug][pid:19364][snclient:1554] limits: GOGC=30%

As you can see the upgrade seems to say it goes through OK, but doesnt restart the service at the end, and when we restart it manually its back to v0.38.

snclient_failed_upgrade_log.txt

[sni]

this logfile is from an automatically triggered update? Or manually?

What basically happens is that snclient downloads the new versions which ends up as snclient.update.exe because it cannot directly overwrite the snclient.exe.
Then it launches the update exe and stops itself. The update exe then detects
it`s filename contains update and copies itself to snclient.exe and starts that one
again.

[q2uantum]

@sni It was from an Automatically triggered one.

We have had a few more of these issues with the recent versions updates.

Checked on this morning and there is an snclient.update.exe in the folder still, so it seems that it is failing to copy itself to the snclient.exe for some reason.