nginx: [emerg] bind() to the all-interfaces address:80 failed (98: Address already in use)

TL;DR

Something already holds port 80: another web server, an old nginx that did not stop, or a container. Find it with ss, stop it or move it, then start nginx. nginx binds cleanly once the port is free.

Error

nginx: [emerg] bind() to the all-interfaces address:80 failed (98: Address already in use)

Steps

1. Find the occupant: run ss -tlnp and look at the process attached to port 80. Expected: a concrete process name and PID, often another nginx or apache.
2. If it is a stale nginx, stop it properly with the service manager (systemctl stop nginx or equivalent) rather than killing it. Expected: the port frees up.
3. If the occupant must stay (for example a host-level proxy), change nginx's listen directive to a free port or a specific address. Expected: no more bind conflict.
4. Validate the config: run nginx -t. Expected: syntax ok and test successful.
5. Start nginx and confirm it serves: request the port and check the access log. Expected: HTTP 200s instead of emerg errors.

When to use

• nginx fails to start with "Address already in use" on port 80 or 443
• After unclean shutdowns leave a listener behind
• Containers and host nginx fighting over the same port

When not to use

• Permission denied binding low ports (capability issue)
• Config syntax errors (different emerg message)

Tool compatibility

• nginx (nginx -t, listen directive); ss -tlnp; systemd service management

Variant phrasings

nginx emerg bind failed 98

Error 98 is EADDRINUSE: find the process on the port with ss -tlnp and resolve the conflict.

two nginx instances port 80

Stop the stale one via the service manager; killing the master without cleanup leaves workers holding the port.

Why it happens

Only one process can bind a given address and port. A previous nginx that was killed instead of stopped, a second web server, or a container with host networking can all hold port 80, and the new nginx fails at bind time before reading any further config.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_i6jKFUvpywdwpovbGcewlA