Errors - Polymarket Documentation

The API returns descriptive error messages when a request is rejected. Below are the errors you may encounter when placing or cancelling orders.

Order Placement Errors

Error	Condition
`invalid signature`	EIP-712 signature verification or timestamp failed
`signature expired`	Signature older than 5 minutes
`account not found for proxy`	Signer proxy not linked to any account
`no orders provided`	Empty order array
`FOK orders cannot be post-only`	FOK + `post_only=true`
`IOC orders cannot be post-only`	IOC + `post_only=true`
`GTC orders require a price`	GTC without price
`price cannot be zero`	Price = 0
`client order id cannot be all zeros`	Client order ID is all zeros
`price exceeds allowed decimal places`	Too many decimal places in price
`price exceeds allowed significant figures`	More than 5 significant figures in price
`quantity must be positive`	Quantity is zero or negative
`quantity exceeds allowed decimal places`	Too many decimal places in quantity
`quantity exceeds allowed significant figures`	More than 5 significant figures in quantity
`command expired`	`exp_ms` is in the past
`command expiry too far in future`	`exp_ms` is more than 5 seconds from now

Order Cancellation Errors

Error	Condition
`order_not_found`	Order doesn’t exist
`order_not_pending_risk`	Order is in the risk engine
`order_not_pending_engine`	Order is in engine matching
`order_not_in_orderbook`	Order is not in the active book

Auto-Cancel Errors

Returned when arming the auto-cancel switch with PATCH /v1/trade/auto-cancel. Disarming skips these checks and is always allowed. A deadline already in the past is rejected earlier with a plain 400 message.

Error	Condition
`auto_cancel_deadline_too_soon`	Deadline is less than 5 seconds in the future
`auto_cancel_daily_limit_reached`	Account already triggered auto-cancel the maximum number of times this UTC day
`auto_cancel_in_flight`	A previous trigger is still cancelling the account’s open orders

auto_cancel_in_flight is transient. Arming succeeds once the engine finishes the earlier cancellation.

Isolated Margin Adjustment Errors

These stable identifiers are returned when an isolated margin adjustment is rejected after sequencing. Gateway signature validation can reject a stale or future-skewed timestamp earlier as invalid signature; that request never reaches sequencing.

Error	Condition
`position_not_found`	The target open position does not exist
`invalid_margin_mode`	The target position is not using isolated margin
`invalid_margin_amount`	The amount is zero, over-precise, or cannot be represented safely
`insufficient_margin`	An addition exceeds available, unreserved collateral
`account_liquidating`	Cross liquidation is active, or the target isolated position is liquidating
`margin_below_required_initial`	A removal would leave position equity below current required initial margin
`invalid_margin_signature_timestamp`	Sequencer found the timestamp over five minutes old or one minute ahead
`signature_already_used`	The exact signed margin request has already been ingested