The resource is locked.
When to use it
WebDAV, or a record being edited by someone else.
Common causes and fixes
423 comes from WebDAV: a file or collection is locked, usually because another client holds a LOCK on it. You meet it with Nextcloud, SharePoint or Office documents opened from a WebDAV share, often after a crashed client left a lock behind. Locks have timeouts and eventually expire; in Nextcloud an admin can clear stale ones, which live in the database or Redis.
Outside WebDAV, some APIs use 423 for a record being edited by someone else, or an account locked after too many failed logins. Generic clients don’t know it well, so include a clear message and, if possible, Retry-After with the lock’s remaining time. 409 is the more widely understood choice for edit conflicts, and 429 or 403 for login lockouts.
Client error (4xx)
4xx codes are client errors: the request itself is wrong, unauthorised or points at something that isn’t there. Retrying the same request won’t help.
What it looks like
HTTP/1.1 423 LockedHow to send it
| Node.js / Express | res.status(423).end() |
|---|---|
| Python / Flask | return '', 423 |
| nginx | return 423; |
How to check it
curl -s -o /dev/null -w "%{http_code}\n" https://example.com/