wg-quick: 'wg0' already exists

wg-quick: 'wg0' already exists

TL;DR: a wg0 interface is already up from an earlier run, so wg-quick will not create a second one. Run sudo wg-quick down wg0 first, then up again. This bites when a previous up half-succeeded or the config was applied by hand.

wg-quick: 'wg0' already exists

Steps

1. Take the existing interface down:

sudo wg-quick down wg0

Expected: no output.

2. Confirm it is gone:

ip link show wg0

Expected: Device "wg0" does not exist.

3. Bring it up fresh:

sudo wg-quick up wg0

Expected: the interface is created and wg show wg0 lists peers.

When this applies

• re-running wg-quick up after it was killed midway
• scripts that call up without a matching down
• the interface was created manually and then wg-quick ran

When it doesnt

• RTNETLINK answers: File exists — leftover addresses, a level deeper than this
• config file missing — different error entirely
• you actually want two tunnels — give the second a different interface name

Compatibility

wireguard-tools wg-quick on Linux.

Other phrasings

• wg-quick interface already exists
• cannot create wg0: exists

Why it happens

wg-quick refuses to create an interface that already exists rather than silently reusing it, because reusing it could mean applying a new config to a live tunnel halfway.

Edge cases

• If down claims the interface is not defined but ip link shows it, delete it directly with ip link delete wg0.
• Persistent interfaces managed by systemd-networkd should be restarted through the service, not wg-quick.