How to Fix: Proxmox apt-get update Failed (Exit Code 100)

What Causes Exit Code 100 in Proxmox?

This error appears when APT hits something it cannot process. Common causes include:

• Enterprise repo enabled without a subscription

• Old or invalid Proxmox repositories

• Expired Debian or security repo URLs

• Broken or partially installed packages

• Missing GPG keys

• Incorrect sources.list configuration

Now let’s fix it step-by-step.

Method 1: Disable the Enterprise Repository

Open the file /etc/apt/sources.list.d/pve-enterprise.list and comment out the enterprise line by placing a # in front of it. Once saved, the enterprise repo will no longer trigger update failures.

Method 2: Enable the Proxmox No-Subscription Repository

You need to enable the Proxmox no-subscription repository. Create or open the file /etc/apt/sources.list.d/pve-no-subscription.list and add the correct no-subscription line for your Proxmox version. Saving this file and running apt-get update usually resolves the update failure immediately.

nano /etc/apt/sources.list.d/pve-no-subscription.list deb http://download.proxmox.com/debian/pve bookworm pve-no-subscription

apt-get update

Method 3: Fix Debian Sources (Common Issue)

Sometimes the default Debian repos get outdated or removed. Check your main apt sources:

nano /etc/apt/sources.list

Recommended Debian 12 (Bookworm) sources:

deb http://deb.debian.org/debian bookworm main contrib deb http://security.debian.org/debian-security bookworm-security main contrib deb http://deb.debian.org/debian bookworm-updates main contrib

Remove any outdated or broken URLs.

Method 4: Install Missing GPG Keys

If the error shows NO_PUBKEY, run:

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys YOUR_MISSING_KEY

Or for Proxmox:

wget https://enterprise.proxmox.com/debian/proxmox-release-bookworm.gpg -O /etc/apt/trusted.gpg.d/proxmox-release-bookworm.gpg

Then:

apt-get update

Method 5: Fix Broken Packages

If APT complains about broken dependencies, run:

apt --fix-broken install

Then:

apt-get update