FOK orders are filled or killed
A Fill-or-Kill order could not be fully satisfied.
A fill-or-kill order found less liquidity than it needed, so none of it filled. Use a smaller size, a limit order, or FAK if partial fills are acceptable.
Retry? Safe to retry
This is transient. Retry with exponential backoff and random jitter so a fleet of workers doesn't retry in step.
Any authenticated CLOB endpoint can return this.
Handling it in code
The CLOB API returns errors as {"error": "..."}. It also rewrites status codes by message, so branch on the text: anything containing "not found" becomes 404 and anything containing "unauthorized" becomes 401.
r = session.post(url, json=payload, headers=headers)
if r.status_code >= 400:
msg = r.json().get("error", "")
if "FOK orders are filled or killed" in msg:
backoff_and_retry()Related errors
For errors Polymarket doesn't document, like "order manager not ready" or 403s from the edge, see the full error guide.
Message and status from Polymarket's error reference, synced 2026-10-04.