# Contract errors

This section contains selected, most frequently occurring errors the protocol may revert with.

## Router

### swap: EXPIRED

Thrown when the current block's timestamp is greater than the provided `_deadline` of a swap.

```solidity
require(block.timestamp <= _deadline, "RC:_swapExactTokensForTokens:EXPIRED");
```

### swap: BELOW\_MINIMUM

Thrown when the minimum acceptable output amount `_amountOutMin` of a swap is not met.

```solidity
require(amountOut >= _amountOutMin, "RC:_swapExactTokensForTokens:BELOW_MINIMUM");
```

***

## SwapPool

### withdraw: MINIMUM\_AMOUNT

Thrown when the withdraw amount `_payoutAmount` is less than the accepted minimum amount `_minimumAmount`.

```solidity
require(payoutAmount_ >= _minimumAmount, "SP:withdraw:MINIMUM_AMOUNT");
```

### backstopBurn: TIMELOCK

Thrown when the user `_owner` attempts to execute a `backstopBurn` in the same block as their last deposit, and the shares to burn exceed the balance held before that deposit.

```solidity
if (block.number == lastDepositAt[_owner]) {
    require(userBalance - lastDepositAmount[_owner] >= _sharesToBurn, "SP:backstopBurn:TIMELOCK");
}
```

### backstopBurn: INSUFFICIENT\_COVERAGE

Thrown when the coverage ratio of the swap pool is more or would still be greater than 100% for the amount of swap pool LP shares to be redeemed for backstop pool liquidity.

```solidity
require(oldReserve <= oldTotalLiabilities - amount_, "SP:backstopBurn:INSUFFICIENT_COVERAGE");
```

### backstopDrain: INSUFFICIENT\_COVERAGE

Thrown when the coverage ratio of the swap pool is less or would become lower than 100% for the amount of backstop pool LP shares to be withdrawn for swap pool liquidity.

```solidity
require(oldReserve >= oldTotalLiabilities + _amount, "SP:backstopDrain:INSUFFICIENT_COVERAGE");
```

### swap: EXCEEDS\_MAX\_COVERAGE\_RATIO

Thrown when the coverage ratio of the swap pool would exceed 200% after swap inequire(

```solidity
require(
    (oldReserve + effectiveAmount_) <= (maxCoverageRatioForSwapIn * oldTotalLiabilities) / 100,
    "SP:quoteSwapInto:EXCEEDS_MAX_COVERAGE_RATIO"
 );
```

***

## BackstopPool

### withdraw: MINIMUM\_AMOUNT

Thrown when the withdraw amount `_payoutAmount` is less than the accepted minimum amount `_minimumAmount`.

```solidity
require(payoutAmount_ >= _minimumAmount, "BC:finalizeWithdrawBackstopLiquidity:MINIMUM_AMOUNT");
```

### redeemSwapPoolShares: MIN\_AMOUNT

Thrown when the amount of the to be withdrawn backstop pool LP shares for swap pool liquidity is less the accepted minimum amount `_minAmount`.

```solidity
require(amountOut_ >= _minAmountOut, "BC:_redeemSwapPoolShares:MIN_AMOUNT");
```