April 28, 2026

April 28, 2026 · View on GitHub

This is what I observed running a live bot through the V1 → V2 cutover. Times are UTC. If you ran a bot during this window, this should help you reconcile what your error logs are showing.

TL;DR

Polymarket announced a 1-hour cutover. The actual disruption was ~6 hours of mixed states (cancel-only, partial V2, full V2). Bots that aggressively retried during this window racked up 503 errors with no on-chain effect. Bots that backed off cleanly and waited for V2-ready signal resumed without incident.

The window

Time (UTC)	State	What worked	What didn't
11:00	Cutover begins. Polymarket front-end shows maintenance banner.	Reads (orderbook, balance, market, positions)	New orders (POST /order → HTTP 503 cancel-only)
11:00–13:00	Pure cancel-only window. V1 contracts paused; V2 not yet active for general traffic.	Cancels of pre-existing V1 orders	New orders, edits
13:00–14:30	V2 contracts activated for trading but bots still on V1 SDK kept getting 503. The V1 SDK was talking to V1 endpoints which were no longer accepting orders.	UI users who'd already migrated their wallet	Any V1 SDK code path posting orders
14:30–16:00	Mixed state. Some markets routable on V2; others still flapping.	V2 SDK against migrated wallets	V1 SDK; V2 SDK against un-migrated wallets (allowance errors)
16:00 onward	Stable V2. Order posting reliable for migrated wallets.	Everything, on V2	Anyone still on V1 imports (HTTP 503 / kwarg errors)

Pre-existing state at cutover

Open orders: All open V1 limit orders were cancelled at 11:00 UTC. If your bot tracked open-order state in its own DB, that DB became stale at 11:00. Re-fetch open orders from the V2 API after migration; don't trust any local cache from before the cutover.

Open positions: Untouched. Positions resolve normally on the existing market schedule. The migration only changed the trading layer — settlement and resolution work the same.

USDC.e balance: Not auto-migrated. After triggering the migration prompt in the UI (manual trade of ≥5 shares), your USDC.e is wrapped 1:1 into pUSD. The wrap is reversible — pUSD can be unwrapped back to USDC.e at any time via the same UI.

What the bot saw

Logged errors during the 11:00–16:00 window, by phase:

Phase 1 (11:00–13:00 — pure cancel-only):

HTTP 503: {"error":"Trading is currently cancel-only. New orders are not accepted, but cancels are allowed."}

This was the dominant error. Reads succeeded. POST /order failed.

Phase 2 (13:00–14:30 — V1 SDK pointing at V1 endpoints, V1 endpoints disabled):

HTTP 503 (same message)

Indistinguishable from Phase 1 from the bot's perspective. The fix was: stop retrying, switch SDK, switch wallet allowances, then resume.

Phase 3 (14:30 onward — V2 SDK against un-migrated wallet):

HTTP 400: {"error":"insufficient allowance for V2 CTF Exchange"}

This was the signal that you needed to do the manual UI migration trade. The SDK couldn't trigger it.

What I did, in order

Time	Action	Result
11:05	Detected first 503. Paused bot via `MAX_ENTRY_PRICE = 0.0` config flag.	Bot stopped firing buys; existing positions kept being monitored.
11:30	Read Polymarket V2 announcement and SDK release notes.	Confirmed the change list (imports, kwargs, contracts).
12:00	`pip install py-clob-client-v2` in venv. Did NOT uninstall V1.	Both SDKs available; rollback path preserved.
12:15	`sed -i '' 's\|from py_clob_client\.\|from py_clob_client_v2.\|g' agents/trader/*.py`	All imports updated.
12:20	`sed -i '' 's\|orderType="FOK"\|order_type="FOK"\|g' agents/trader/*.py`	Kwarg renamed in 2 places.
12:30	Ran smoke test: `python -c "from py_clob_client_v2.client import ClobClient; print('ok')"`	Passed.
12:45	Opened polymarket.com, clicked Trade on a small market, signed migration approvals. Cost ~$0.01 in MATIC gas.	Wallet now holds pUSD; V2 allowances appeared in `get_balance_allowance` response.
13:00	Manual test: posted a 1-share order, watched it settle on-chain.	Order filled. Migration verified.
14:00	Resumed bot at half-size (`POSITION_SIZE_USD = 5.0` instead of 10).	First 3 orders went through cleanly.
17:00	Confirmed 6 hours of clean operation. Returned to normal POSITION_SIZE_USD.	Back to production.

Total wall time: 4 hours (12:00–16:00 of active work, plus 2 hours of waiting for V2 to stabilize before resuming).

Lessons

Don't retry blindly. A bot that retries every 30s for 6 hours through cancel-only mode generates ~720 failed POST requests, fills your error log, and risks rate-limiting. Pause the bot the moment you see the first 503 and read the error message.
Keep both SDKs installed during cutover. pip install py-clob-client-v2 does NOT remove the V1 package. If V2 misbehaves, you can revert imports in 30 seconds. After V2 is stable for 24h, uninstall V1.
The UI migration trade is the only allowance trigger. No SDK call, no manual update_balance_allowance, no copying-and-resigning of approvals on Polygonscan will work. You must click Trade in the Polymarket UI on any market for ≥5 shares. Once approved on-chain, it's permanent.
Test with one tiny order before resuming production volume. A clean manual order through the V2 path proves: SDK works, wallet is migrated, contracts approved, signing flow correct. If that fails, your bot will fail too — debug at the small scale.
Pre-existing positions are unaffected. If your bot has open positions at cutover, they keep monitoring fine. Only the trade-post path is broken during the window.