How to Fix Docker “Permission Denied” Error on Proxmox After System Update

Updating LXCs After a Long Break

It's been ages since I last updated my LXCs, and one day I suddenly thought — today is the day.
I started with the most obvious choice: the entry point to all other services — Nginx Proxy Manager.

Running the Update

As usual, I ran:

apt update
apt upgrade

After a few minutes the upgrade finished, but I quickly realized that none of my self‑hosted services were reachable. That could only mean one thing — the reverse proxy was down.

Checking Docker

A quick look at docker ps showed that no containers were running.
I navigated to the directory containing my entire docker-compose setup and ran:

docker compose up

…only to see this friendly error:

Error response from daemon: failed to create task for container: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: open sysctl net.ipv4.ip_unprivileged_port_start file: reopen fd 8: permission denied

What Caused the Problem?

Fortunately, the solution turned out to be simple — no need to roll back Docker or modify configs.

The issue was an outdated Proxmox host.

Fixing the Host

I logged into my PVE host and performed:

apt update && apt upgrade

In the end, my Proxmox instance jumped from v8.4.2 to v8.4.16, and just like that, Nginx Proxy Manager was running again.