I'm currently on a trial and loving it! I’ll definitely be purchasing a license. However, I'm facing a strange issue. After every clean system reboot, the array starts up fine, but the Docker service fails to start. In the Docker tab, I see the message: "Docker Service failed to start."

In the logs, I see the following:

Oct 2 17:48:24 unraid rc.docker: Starting Docker daemon...
Oct 2 17:48:25 unraid sysDrivers: SysDrivers Build Complete
Oct 2 17:49:00 unraid rc.docker: Docker daemon... Failed.
Oct 2 17:51:20 unraid webgui: docker stats error: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

If I recreate the Docker image as per the documentation, everything works fine again, but it's inconvenient to do this after every reboot or shutdown. I don't think this is caused by a corrupted docker image.

Any ideas on how to fix this?

unraid-diagnostics-20251002-1754.zip

54 minutes ago, lmag said:

f I recreate the Docker image as per the documentation, everything works fine again

Are you filling it up?

50G is larger than default, and often more than needed unless you have something misconfigured.

A common reason for filling docker.img is an application writing to a path that isn't mapped to the host.

Try recreating the docker image:

https://docs.unraid.net/unraid-os/troubleshooting/common-issues/docker-troubleshooting/#re-creating-the-docker-image-file

Then:

https://docs.unraid.net/unraid-os/troubleshooting/common-issues/docker-troubleshooting/#reinstalling-docker-applications

Also see below if you have any custom docker networks:

https://docs.unraid.net/unraid-os/troubleshooting/common-issues/docker-troubleshooting/#restoring-docker-custom-networks

14 hours ago, trurl said:

Are you filling it up?

50G is larger than default, and often more than needed unless you have something misconfigured.

A common reason for filling docker.img is an application writing to a path that isn't mapped to the host.

I don't think it is fiiling up, I was just testing different configurations for debugging.

Checked mappings, all seems ok.

5 hours ago, JorgeB said:

Try recreating the docker image:

https://docs.unraid.net/unraid-os/troubleshooting/common-issues/docker-troubleshooting/#re-creating-the-docker-image-file

Then:

https://docs.unraid.net/unraid-os/troubleshooting/common-issues/docker-troubleshooting/#reinstalling-docker-applications

Also see below if you have any custom docker networks:

https://docs.unraid.net/unraid-os/troubleshooting/common-issues/docker-troubleshooting/#restoring-docker-custom-networks

Already did that many times. As I said, it works, but when rebooting (even if stopping array first), the problem always occurs again.

Any more ideas? I already sent the diagnostics file, if that helps.

Thanks for helping!

Edited October 3, 2025Oct 3 by lmag

43 minutes ago, lmag said:

I already sent the diagnostics file, if that helps.

Diags show the service failing to start, not why, at least as far as I can tell, and recreating the image should resolve it, if you re-create the image, then stop the array restart the array, does it still work?

4 hours ago, lmag said:

Checked mappings, all seems ok

Mapping can seem OK, but if the application itself is writing to a path that isn't mapped, that path is inside docker.img and will fill it.

4 hours ago, JorgeB said:

Diags show the service failing to start, not why, at least as far as I can tell, and recreating the image should resolve it, if you re-create the image, then stop the array restart the array, does it still work?

Yes, everything works fine when I do that, but only until the next reboot (whether I stop the array first or not). I've done this maybe half a dozen times.

53 minutes ago, trurl said:

Mapping can seem OK, but if the application itself is writing to a path that isn't mapped, that path is inside docker.img and will fill it.

Got it. I’ve checked all the applications, and I don’t think any of them is causing this issue.

Also, if I’m understanding correctly, this would show the used space inside the image with all the apps running, and it's well below 50GB:

root@unraid:~# docker system df
TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
Images          43        43        16.83GB   542.2MB (3%)
Containers      47        47        1.983GB   0B (0%)
Local Volumes   3         3         0B        0B
Build Cache     0         0         0B        0B

It’s not the end of the world if I never have to reboot, but when I do, it’s really inconvenient and frustrating. It feels like something’s broken = /

I'm afraid that I don't have an idea what the issue could be if it works after an array stop, for most purposes, it should be the same as a reboot, unless you are keeping something needed in RAM, which would be lost after a reboot.

12 hours ago, JorgeB said:

unless you are keeping something needed in RAM

Container applications can also write to RAM if there is a mapping to something that isn't actual storage.

What do you get from command line with this?

df -h /

Sorry for the delayed response. Busy weekend.

On 10/4/2025 at 3:52 AM, JorgeB said:

I'm afraid that I don't have an idea what the issue could be if it works after an array stop, for most purposes, it should be the same as a reboot, unless you are keeping something needed in RAM, which would be lost after a reboot.

That’s what I thought, which is why it doesn’t make much sense. It also wasn’t happening right after deploying the containers for the first time.

What could be causing the docker service to fail to start? Maybe I should try disabling the plugins. Could one of them be responsible? Or do you have any other debugging steps you’d recommend?

On 10/4/2025 at 4:03 PM, trurl said:

Container applications can also write to RAM if there is a mapping to something that isn't actual storage.

What do you get from command line with this?

df -h /

Nothing out of the expected:

Filesystem      Size  Used Avail Use% Mounted on
rootfs           16G  915M   15G   6% /

Thanks again for your help!

2 hours ago, lmag said:

What could be causing the docker service to fail to start? Maybe I should try disabling the plugins.

You can try booting in safe mode and see if the same thing happens, that will rule out the plugins. If it's not that, it could be a specific container; you can try just starting half the containers. If there are no issues, try the other half, then keep drilling down.

Unfortunately, the same thing happens when booting in safe mode. Also, none of the containers seem to be the cause.

To make matters worse, every time I reboot, the system fails to start properly and I can't access the webui. I have to do a physical reset, and then it starts normally (although the same Docker issue remains).

None of this was happening after install.

At this point, should I just start over? What is the best way to reset the system without losing data?

Also, my trial is about to expire in 1 day and 8 hours. When I try to extend it for another 15 days, I get a vague error and no change in expiration. I did stop the array first.

Not a great experience the problems started =/

50 minutes ago, lmag said:

What is the best way to reset the system without losing data?

As long as you assign your drives correctly you shouldn't lose any data.

34 minutes ago, trurl said:

As long as you assign your drives correctly you shouldn't lose any data.

Can you describe the general steps I should follow to do that? Just a very general overview. Thanks!

Take a screenshot of the array assignments, start with a new install, and reassign the devices as they were.