Polymarket halted trading on its order book for four hours and 17 minutes on Monday after a failure it had declared resolved five hours earlier recurred, according to the platform’s status page.
Trading was paused at 06:30 UTC, and the incident was marked resolved at 10:47. Both incidents that day carry the same description: delayed open order read responses.
The Timeline
The first incident opened at 00:40 UTC as a major outage affecting the Trading API and prediction markets. Polymarket moved to cancel-only mode at 01:06 and marked it resolved at 01:12, a duration of 32 minutes.
The second opened at 06:23 UTC as a partial outage and escalated seven minutes later, with Polymarket pausing trading while it worked on the incident.
Resolution took longer than the platform initially expected. At 08:29 it targeted resumption by 10:00 UTC at the latest. At 09:40 it said the fix was still being applied and moved the target to 11:00. At 10:23 it confirmed the fix had been applied and said cancel-only mode would run until 10:40. The incident was marked resolved at 10:47.
Cancel-only mode allows traders to withdraw existing orders but not place new ones.
A Recently Rebuilt Order Book
The affected system is not legacy infrastructure. Polymarket rebuilt its central limit order book in April, launching CLOB v2 on April 28 after a one-hour maintenance window in which trading was halted and order books cleared. The upgrade brought new exchange contracts, a rewritten CLOB backend and pUSD, an ERC-20 token on Polygon backed 1:1 by USDC as primary collateral. Legacy V1 SDKs were retired at the same time.
The platform has grown substantially on that infrastructure. Polymarket’s total value locked (TVL) crossed $500 million following the rollout, reaching roughly $514 million with open interest at a similar level and $4.49 billion in 30-day volume, according to figures recorded in late April.
What Stayed Up
The outage was confined to the order book. Polymarket’s web app, account access, websocket services, markets and position data, and on-chain settlement through Polygon all remained operational throughout both incidents.
Its perpetual products—listed separately on the status page as perpetuals trading, API, and market data—were also unaffected. Polymarket introduced perpetual futures in April 2026 as a separate product from its binary event contracts, which is why the status page lists perpetuals trading, API and market data as distinct services from the prediction markets group.
What Polymarket Has Not Said
The platform has published no cause beyond the symptom in the incident title and no explanation of why the first fix did not hold.
It has not said whether any orders were affected, whether traders were unable to exit positions during the pause, or whether any market resolved while the order book was down.
The Crypto Times has asked Polymarket what caused the delayed order reads, whether the two incidents were the same underlying failure, whether any open orders or positions were affected, whether any market was resolved during the halt, and whether users unable to trade will be compensated at 11:03 AM UTC. This report will be updated with any response.
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