Cloudron down after Ubuntu/Docker update (Docker service fails to start)

[osobo]

Hello all,

Just wanted to share what happened to me and the way to fix it in case you experience the same issue. @cloudron_admin please delete the post if not relevant.

After applying recent Ubuntu security updates and rebooting, my Cloudron instance became unreachable.

cloudron-support --troubleshoot

showed Docker was down, and

systemctl start docker

failed while running dockerd manually worked fine.

I've worked it out with the support of ChatGPT. Root cause : An outdated Cloudron systemd override file:

/etc/systemd/system/docker.service.d/cloudron.conf

This override replaces Docker’s default ExecStart and uses older flags (like cgroupfs) that are no longer compatible with newer Docker versions. As a result, Docker fails to start via systemd.

Fix : Remove the override and reload systemd:

sudo rm /etc/systemd/system/docker.service.d/cloudron.conf
sudo systemctl daemon-reexec
sudo systemctl daemon-reload
sudo systemctl restart docker

Verify Docker is running:

systemctl status docker

Then restart Cloudron:

sudo systemctl restart box

Result

Docker starts normally again, containers come back up, and the Cloudron dashboard becomes accessible.

Notes
Modern Docker versions already handle most of the options that the override was forcing.
Removing the override lets Docker run with its correct defaults (including proper cgroup handling).
This issue may appear after unattended upgrades or manual system updates.

Hope this helps anyone running into the same issue

[jdbaker]

Thanks!
This happened with my Hostinger VPS installation a couple days ago, so I rolled back to a snapshot. I had another Ubuntu security update pending reboot this morning, so after reading your post, I figured I'd give it a whirl, but this time the Cloudron came back up on its own.

[Valexico]

Same issue here, same solution except I had to reboot the server (sudo systemctl restart docker not working)
I had a bit of panic for a sunday evening !
Waiting to hear from the Cloudron team to confirm which are the recommended fix !

For the records, it happened after my scheduled weekly cloudron update + reboot. So I guess it could happen to any user

[osobo]

@jdbaker Glad to hear everything is back on track. Indeed my VPS is hosted by Hostinger too.

[james]

Hello @osobo
Do I understand it correct that you did a manual system update and this was not an unattended security update?

[Valexico]

Hi @james
In my case i Didn't do any manual update : I let cloudron manage updates I just schedule a reboot once a week

[osobo]

Hello @james. I think so. Following Cloudron’s notification to reboot the server I’ve simply clicked on the « reboot » link within the dashboard and lost the access from there.

[james]

Hello @valexico and @osobo
Thanks for that.
Can you two please ssh into your Cloudron server and post the output of following command?

docker --version

[osobo]

@james Docker version 29.1.5, build 0e6fee6

[Valexico]

Same here
Docker version 29.1.5, build 0e6fee6

[james]

Hello @osobo and @valexico
Thanks.
Do you still have the /etc/systemd/system/docker.service.d/cloudron.conf file?
Because on two of my Cloudron systems it is also Docker version 29.1.5, build 0e6fee6 and there was no issue with docker.

[Valexico]

No I deleted the file to fix the issue as described by @osobo

[Valexico]

my claude chat if it helps
https://claude.ai/share/acd62c73-b4e5-4e49-9e84-7e06d4229815

[osobo]

Same here. The file has been deleted with the fix.

[jdbaker]

For what its worth, the issue occurred for me last Thursday night after using the reboot option in the dashboard, as instructed by the typical Cloudron notification. The VPS came back up, but the Cloudron dashboard was unreachable. In the VPS terminal, the troubleshooter showed docker was not starting. Two additional VPS reboots did not resolve it, so I simply rolled back, and then everything appeared to be working.

Later that night, Cloudron updated from 9.1.5 to 9.1.6.

When another reboot notification appeared yesterday, I took another snapshot of the VPS before rebooting, and everything came back up just fine.

However, I did NOT delete my cloudron.conf file, and it still exists.

My docker version is 29.1.5, build 0e6fee6.

[Valexico]

@james
So, should we do something to restore our cloudron to nominal configuration ? Recreate this cloudron.conf file somehow ?

[james]

Hello @valexico

@Valexico said:

So, should we do something to restore our cloudron to nominal configuration ? Recreate this cloudron.conf file somehow ?

That would be best I think.
If this would reproduce the previous issue, that be interesting to get an understanding what is causing this.

The default content from /etc/systemd/system/docker.service.d/cloudron.conf is:

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H fd:// --log-driver=journald --exec-opt native.cgroupdriver=cgroupfs --storage-driver=overlay2 --experimental --ip6tables --userland-proxy=false

[Valexico]

hi @james

I tried to restore this file but docker won't start.

Claude analysis :

• systemd (file cloudron.conf) passes --log-driver=journald
• But /etc/docker/daemon.json also defines log-driver: json-file

So what is the official fix ?

Here are some logs :

tail -n 40 ../yellowtent/platformdata/logs/box.log
  stdout: '',
  stdoutString: '',
  stdoutLineCount: 0,
  stderr: 'Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?\n',
  stderrString: 'Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?\n',
  stderrLineCount: 1,
  code: 1,
  signal: null,
  timedOut: false,
  terminated: false
}
2026-04-20T20:18:28.212Z shell: docker: docker update --memory 268435456 --memory-swap -1 redis-9d1726c8-d217-45ab-ac30-0ec5c01c4cf0 errored BoxError: docker exited with code 1 signal null
    at ChildProcess.<anonymous> (file:///home/yellowtent/box/src/shell.js:70:23)
    at ChildProcess.emit (node:events:508:28)
    at maybeClose (node:internal/child_process:1101:16)
    at Socket.<anonymous> (node:internal/child_process:457:11)
    at Socket.emit (node:events:508:28)
    at Pipe.<anonymous> (node:net:346:12) {
  reason: 'Shell Error',
  details: {},
  stdout: '',
  stdoutString: '',
  stdoutLineCount: 0,
  stderr: 'Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?\n',
  stderrString: 'Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?\n',
  stderrLineCount: 1,
  code: 1,
  signal: null,
  timedOut: false,
  terminated: false
}
2026-04-20T20:18:28.213Z cron: handleAutoupdateConfigChanged: schedule - 00 00 1,2,3,4,5 * * 0,4/Europe/Paris, policy - platform_and_apps
2026-04-20T20:18:28.215Z cron: Dynamic DNS setting changed to false
2026-04-20T20:18:28.216Z dockerproxy: start: listening on 172.18.0.1:3003
2026-04-20T20:18:28.216Z From uncaughtException handler.
2026-04-20T20:18:28.216Z Error: listen EADDRNOTAVAIL: address not available 172.18.0.1:3003
2026-04-20T20:18:28.216Z     at Server.setupListenHandle [as _listen2] (node:net:1918:21)
2026-04-20T20:18:28.216Z     at listenInCluster (node:net:1997:12)
2026-04-20T20:18:28.216Z     at node:net:2206:7
2026-04-20T20:18:28.216Z     at process.processTicksAndRejections (node:internal/process/task_queues:89:21)

sudo journalctl -u docker --since "today" | grep -A5 "error\|Error\|failed\|Failed" | head -60
Apr 20 09:14:20 srv565755 dockerd[928]: time="2026-04-20T09:14:20.051807769Z" level=warning msg="ShouldRestart failed, container will not be restarted" container=4f0cb8c35e7ba64d6a081361646cb651cc3956442e62c97946f0d15edd6de455 daemonShuttingDown=false error="restart canceled" execDuration=13h52m56.033484743s exitStatus="{0 2026-04-20 09:14:19.681121204 +0000 UTC}" hasBeenManuallyStopped=true restartCount=0
Apr 20 09:16:48 srv565755 dockerd[928]: time="2026-04-20T09:16:48.421429471Z" level=info msg="Configured log driver does not support reads, enabling local file cache for container logs" container=951df08d2fe64f854504c7f945d526f99347a3b7ffc6b5742479f18ee8595776 driver=syslog
Apr 20 09:16:48 srv565755 dockerd[928]: time="2026-04-20T09:16:48.647044948Z" level=info msg="Skipping check for route to send NA, EMSGSIZE" eid=587f20e087dc ep=1c5d0773-9eca-48f8-945e-83733391299d net=cloudron nid=b08cee04d967
Apr 20 09:16:48 srv565755 dockerd[928]: time="2026-04-20T09:16:48.653269180Z" level=info msg="sbJoin: gwep4 ''->'587f20e087dc', gwep6 ''->'587f20e087dc'" eid=587f20e087dc ep=1c5d0773-9eca-48f8-945e-83733391299d net=cloudron nid=b08cee04d967
Apr 20 11:33:17 srv565755 dockerd[928]: time="2026-04-20T11:33:17.566840739Z" level=info msg="ignoring event" container=951df08d2fe64f854504c7f945d526f99347a3b7ffc6b5742479f18ee8595776 module=libcontainerd namespace=moby topic=/tasks/delete type="*events.TaskDelete"
Apr 20 11:33:17 srv565755 dockerd[928]: time="2026-04-20T11:33:17.626250628Z" level=warning msg="ShouldRestart failed, container will not be restarted" container=951df08d2fe64f854504c7f945d526f99347a3b7ffc6b5742479f18ee8595776 daemonShuttingDown=false error="restart canceled" execDuration=2h16m29.209514787s exitStatus="{0 2026-04-20 11:33:17.50260464 +0000 UTC}" hasBeenManuallyStopped=true restartCount=0
Apr 20 11:33:31 srv565755 dockerd[928]: time="2026-04-20T11:33:31.302996371Z" level=info msg="Configured log driver does not support reads, enabling local file cache for container logs" container=5cd41c6952e0e4a57df020a068ba8d8ad03a1962cf5166c16def923db4a19678 driver=syslog
Apr 20 11:33:31 srv565755 dockerd[928]: time="2026-04-20T11:33:31.544418039Z" level=info msg="Skipping check for route to send NA, EMSGSIZE" eid=cc6732021dd2 ep=1c5d0773-9eca-48f8-945e-83733391299d net=cloudron nid=b08cee04d967
Apr 20 11:33:31 srv565755 dockerd[928]: time="2026-04-20T11:33:31.550239968Z" level=info msg="sbJoin: gwep4 ''->'cc6732021dd2', gwep6 ''->'cc6732021dd2'" eid=cc6732021dd2 ep=1c5d0773-9eca-48f8-945e-83733391299d net=cloudron nid=b08cee04d967
Apr 20 20:17:06 srv565755 systemd[1]: Stopping docker.service - Docker Application Container Engine...
Apr 20 20:17:06 srv565755 dockerd[928]: time="2026-04-20T20:17:06.327530091Z" level=info msg="Processing signal 'terminated'"
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.546853647Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.555695229Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.555782219Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.555813540Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.566229495Z" level=info msg="ignoring event" container=0b8f6fb173a1d0e2d4dedcbfba65145ed2a57c720caab9bbe67f404771fc0c88 module=libcontainerd namespace=moby topic=/tasks/delete type="*events.TaskDelete"
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.568576383Z" level=info msg="ignoring event" container=b84eb548ee71992483f45e56428929b79bcc8aad1f7023b195c60f659780d168 module=libcontainerd namespace=moby topic=/tasks/delete type="*events.TaskDelete"
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.582046353Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.582069903Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.582693859Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.589390793Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.632285602Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.659873666Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.704349637Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.730620892Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.730674482Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.730804793Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.751950246Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.766076720Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.774481318Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.792120681Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.792250913Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.820107909Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.842432751Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.842499741Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.842352570Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.889893867Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.898854650Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.905530513Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.914025273Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.914073723Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.915739917Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.917869824Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.921901237Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.921959517Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.940298087Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.940385708Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.940415097Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.957654048Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.984816919Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.984879059Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:07 srv565755 dockerd[928]: time="2026-04-20T20:17:07.984904639Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.002561723Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.002633953Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.002662174Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.002688504Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.023282142Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.032926700Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.052743052Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=
Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.052817351Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=

[james]

Hello @valexico
So this is the actuall error:

Apr 20 20:17:08 srv565755 dockerd[928]: time="2026-04-20T20:17:08.052817351Z" level=error msg="Error writing log message" driver=syslog error="dial unix /home/yellowtent/platformdata/logs/syslog.sock: connect: no such file or directory" message=

Can you please check the status of:

systemctl status cloudron-syslog.service