Update Documentation for SSH Connection Issues During Installation

[spectaA]

Hi Coolify Team,

I recently encountered an issue during the installation of Coolify where it was unable to connect to localhost due to SSH connection problems. The specific error message displayed was:

root@host.docker.internal: Permission denied (publickey,password).

After spending several hours troubleshooting, I discovered that the problem was not with Coolify itself, but with the default SSH configuration on Ubuntu Server.

By default, the sshd_config file contains the following rule:
AllowGroups admin
This rule prevents the root user from connecting unless explicitly added to the AllowGroups.

To resolve this issue, I added the root group to the AllowGroups in the sshd_config file as follows:
AllowGroups admin root

I believe it would be beneficial for other users if this information were included in the Coolify installation documentation. This addition could save significant troubleshooting time and help ensure a smoother installation process.

Thank you for considering this request!

[palepinkdot]

Just ran into this problem myself and was able to resolve it with the solution provided.

[rafaseron]

I had this problem now, and unfortunately the AllowGroups admin line did not exist.

I solved the problem by installing Coolify one on top of the other (I ran the 'curl' command without uninstalling the existing installation)

[magnusburton]

Running in to this problem but unfortunately this does not fix the issue. Still searching for a solution

[grazy27]

After spending good 5 hrs on trying to get what's wrong, i finally got an answer.
There's log level 'DEBUG3' for OpenSSH (!= DEBUG), in which it finally said what's wrong:

So, to fix that, run sudo nano /etc/ssh/sshd_config
and append(replace) the next lines

PermitRootLogin yes
PubkeyAcceptedAlgorithms +ssh-ed25519
HostKeyAlgorithms +ssh-ed25519

[Vuurbaard]

Thank you! This seemed to have done the trick on my VPS I have rented (from Contabo). ❤️

[pencilcheck]

I use this instead

PermitRootLogin yes
PubkeyAuthentication yes
PubkeyAcceptedKeyTypes ssh-ed25519-cert-v01@openssh.com,ssh-ed25519

But turns out that for some reason after reboot the private key has changed in coolify, so I had to copy what's in the Keys & Tokens to the file authorized_keys for it to work again, not sure why coolify change the keys after reboot. (I run many installation script, does it actually change the key? that is concerning)

[Smit2553]

Had a simular issue. Neither solution above worked.

My solution was there are 2 different .ssh/authorized_keys files. One in root and one under my user. The .ssh/authorized_keys file under root had the coolify ssh key on the same line as my personal login ssh key causing it to break.

Adding a new line between the two ssh keys fixed the issue.

[DevDams]

I had the same problem and indeed the coolify key was on the same line as my key. This solution helped me

[juandation]

HI! Still having the same issue trying to validate the server:

"Please validate your configuration and connection.
Check this documentation for further help.
Error: No query results for model [App\Models\PrivateKey] 0".

I ran the coolify installation twice (Not manually) and the server still is not being validated. I can connect to my VPs via ssh successfully, and I can login to the coolify admin panel. Any possible solution? I tried all from this thread but nothing is working.

[balogun14]

i had a similar issue all i had to do was uninstall and reinstall again

[SayakSarkar02]

what to uninstall and reinstall?

[Roemie]

I also ran into this while self-hosting Coolify (on Unraid in my case), and for me the root cause wasn’t sshd_config but Coolify’s own private key / server registration state.

A few things that finally solved it:

Ensure the Coolify key actually exists in the DB

docker exec -it Coolify php artisan tinker --execute="dump(App\Models\PrivateKey::all(['id','name'])->toArray());"

If you see Error loading private key or no rows at all, regenerate a key pair in the UI and make sure the public key gets added (on its own line) to ~/.ssh/authorized_keys on the target host.

Sentinel must be running with a valid token

docker run -d \
  --name coolify-sentinel \
  -e SENTINEL_TOKEN="your_random_hex_token" \
  -e SERVER_ID="localhost" \
  -v /var/run/docker.sock:/var/run/docker.sock \
  ghcr.io/coollabsio/sentinel:latest

Then update the server row inside Coolify with that token if the UI doesn’t expose a field yet.

Set a proper FQDN in Instance Settings — Coolify won’t let you enable Sentinel with just an IP.
Even for local installs, using a fake domain (e.g. unraid.local) mapped via /etc/hosts or --add-host in Docker parameters worked for me.

After those three steps the “No query results for model [App\Models\PrivateKey] 0” error went away, and Sentinel synced properly. From there I could validate the server and deploy apps without further SSH issues.

[madsaylor]

Lol that's amazing.
I did One Click install by Digital Ocean and got this exact problem. And nothing is working. None of the solutions.
Destroyed droplet started another one - still the same.
One-Click out of box install completely broken.
Now I need to dive into PHP, ssh logs and configs. Good times.