What causes "Port $port is in use. You must stop the process using this port. Docs: https://coolify.io/docs Discord: https://coolify.io/discord " in coollabsio/coolify?

SSH to the server and identify the holder: `ss -tulpn | grep -E ':(80|443|8080)\s'`, then stop/disable that service (e.g. systemctl stop nginx).

coollabsio/coolify · error · Exception

Port $port is in use.<br>You must stop the process using thi

Error message

Port $port is in use.<br>You must stop the process using this port.<br><br>Docs: <a target='_blank' class='dark:text-white hover:underline' href='https://coolify.io/docs'>https://coolify.io/docs</a><br>Discord: <a target='_blank' class='dark:text-white hover:underline' href='https://coolify.io/discord'>https://coolify.io/discord</a>

What it means

\Exception thrown from CheckProxy when $fromUI is true and the parallel port-conflict scan finds one of the proxy's required ports (typically 80/443/8080) already bound by another process on the server. The message intentionally embeds HTML links to docs/Discord because it is rendered in the Livewire error toast. Non-UI callers get false (proxy start skipped).

Source

Thrown at app/Actions/Proxy/CheckProxy.php:105

                        // Combine default ports with config ports
                        $portsToCheck = array_merge($portsToCheck, $configPorts);
                    }
                } else {
                    $portsToCheck = [];
                }
            } catch (\Exception $e) {
                Log::error('Error checking proxy: '.$e->getMessage());
            }
            if (count($portsToCheck) === 0) {
                return false;
            }
            $portsToCheck = array_values(array_unique($portsToCheck));
            // Check port conflicts in parallel
            $conflicts = $this->checkPortConflictsInParallel($server, $portsToCheck, $proxyContainerName);
            foreach ($conflicts as $port => $conflict) {
                if ($conflict) {
                    if ($fromUI) {
                        throw new \Exception("Port $port is in use.<br>You must stop the process using this port.<br><br>Docs: <a target='_blank' class='dark:text-white hover:underline' href='https://coolify.io/docs'>https://coolify.io/docs</a><br>Discord: <a target='_blank' class='dark:text-white hover:underline' href='https://coolify.io/discord'>https://coolify.io/discord</a>");
                    } else {
                        return false;
                    }
                }
            }

            return true;
        }
    }

    /**
     * Check multiple ports for conflicts in parallel
     * Returns an array with port => conflict_status mapping
     */
    private function checkPortConflictsInParallel(Server $server, array $ports, string $proxyContainerName): array
    {
        if (empty($ports)) {
            return [];

View on GitHub (pinned to 70b9acc424)

Solutions

SSH to the server and identify the holder: `ss -tulpn | grep -E ':(80|443|8080)\s'`, then stop/disable that service (e.g. systemctl stop nginx).
If the holder is an orphaned coolify-proxy container: `docker rm -f coolify-proxy` (or coolify-proxy_traefik on Swarm) and retry Start Proxy.
If the ports must stay occupied, change the proxy's exposed ports in Coolify's proxy configuration or move the conflicting service elsewhere.

Example fix

# before clicking Start Proxy, on the server
# (find and stop the conflicting process)
ss -tulpn | grep -E ':(80|443|8080)\s'
systemctl stop nginx && systemctl disable nginx
# then retry Start Proxy in the UI

Defensive patterns

Strategy: validation

Validate before calling

// before starting proxy, verify required ports are free on the server
$ports = [80, 443, 8080];
$output = instant_remote_process(['ss -tulpn | grep -E ":(80|443|8080)\\s" || true'], $server, throwError: false);
if (trim((string) $output) !== '') {
    // resolve conflicts before calling Start Proxy
}

Try / catch

try {
    CheckProxy::run($server, true);
} catch (\Exception $e) {
    if (str_contains($e->getMessage(), 'is in use')) {
        // parse the port, prompt user to stop the holder, then retry
    } else {
        throw $e;
    }
}

Prevention

Dedicate servers to Coolify: stop/disable system webservers (nginx/apache) before adding the server.
Check `ss -tulpn` for 80/443/8080 as part of server onboarding.
After Swarm/local mode switches, remove orphaned proxy containers (coolify-proxy vs coolify-proxy_traefik).
Prefer published-port apps over host-network apps on proxy servers to avoid port clashes.

When it happens

Trigger: Starting/restarting coolify-proxy from the UI while nginx, apache, another container, or a second coolify-proxy instance already listens on 80/443/8080; a stale coolify-proxy container still holding ports after a partial restart; Swarm vs non-Swarm name mismatch leaving an orphan container.

Common situations: Fresh server with a pre-existing web server; port changed in proxy config but an old process still bound; duplicated proxy containers (coolify-proxy vs coolify-proxy_traefik) after switching Swarm mode; another app deployed with host networking on the same ports.

Related errors

AI-assisted analysis of coollabsio/coolify@70b9acc424 (2026-08-17). Data as JSON: /api/errors/3e14e1fc4e8fa98a. Report an issue: GitHub.