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Troubleshooting

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Setup issues

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setDomainVerifier transaction reverts

1. Safe executes a transaction where to = the Safe’s own address
2. The call data encodes setDomainVerifier(domainSeparator, composableCowAddress)
3. The ExtensibleFallbackHandler (set as the Safe’s fallback handler) processes it

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Correct setup sequence

1. Set the fallback handler on the Safe to ExtensibleFallbackHandler (0x2f55e8b20D0B9FEFA187AA7d00B6Cbe563605bF5)
2. Register ComposableCoW as domain verifier by calling setDomainVerifier from the Safe to itself
3. Create programmatic orders via ComposableCoW.create()

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Verifying setup is correct

# Read the Safe's fallback handler slot
cast storage <SAFE_ADDRESS> \
  0x6c9a6c4a39284e37ed1cf53d337577d14212a4870fb976a4366c693b939918d5

# Call domainVerifiers on the Safe (via fallback handler)
cast call <SAFE_ADDRESS> \
  "domainVerifiers(address,bytes32)(address)" \
  <SAFE_ADDRESS> \
  <DOMAIN_SEPARATOR>

cast call 0x9008D19f58AAbD9eD0D60971565AA8510560ab41 "domainSeparator()(bytes32)"

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MultiSend atomic setup

// Transaction 1: Set fallback handler
to: <SAFE_ADDRESS>
data: setFallbackHandler(0x2f55e8b20D0B9FEFA187AA7d00B6Cbe563605bF5)

// Transaction 2: Register domain verifier (Safe calls itself)
to: <SAFE_ADDRESS>
data: setDomainVerifier(<DOMAIN_SEPARATOR>, 0xfdaFc9d1902f4e0b84f65F49f244b32b31013b74)

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Order not appearing in explorer

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1. Check if the watch-tower picked it up

• Was the transaction confirmed? Check the tx hash on the block explorer
• Did the event fire? Look for ConditionalOrderCreated in the transaction logs
• Is the watch-tower running for your chain? The public watch-tower covers Ethereum, Gnosis Chain, Arbitrum One, Base, Polygon, Avalanche, Lens, BNB Chain, Linea, Plasma, Ink, and Sepolia
• Is there a delay? The watch-tower processes blocks periodically — wait a few minutes

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2. Check if the order is currently valid

• Balance insufficient — the Safe doesn’t hold enough sell tokens
• Time condition not met — for TWAP, the current part hasn’t started yet
• Guard rejection — a swap guard is blocking the order

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3. Run your own watch-tower for debugging

# Clone and run with debug logging, monitoring only your Safe
git clone https://github.com/cowprotocol/watch-tower
cd watch-tower
yarn install

LOG_LEVEL=DEBUG yarn cli run \
  --config-path ./config.json \
  --only-owner <YOUR_SAFE_ADDRESS> \
  --one-shot

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Foundry / Forge dependency issues

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Missing SignatureVerifierMuxer.sol

forge install cowprotocol/composable-cow

# foundry.toml or remappings.txt
[profile.default]
remappings = [
    "composable-cow/=lib/composable-cow/src/",
    "safe/=lib/composable-cow/lib/safe-contracts/contracts/",
    "safe-contracts/=lib/composable-cow/lib/safe-contracts/contracts/",
]

cd lib/composable-cow
forge install safe-global/safe-contracts --no-commit

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Order stopped being polled unexpectedly

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Root cause

• OrderNotValid(string)
• PollTryNextBlock
• PollTryAtBlock(uint256)
• PollTryAtEpoch(uint256, uint256)
• PollNever(string)

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Common triggers

• Arithmetic overflow/underflow — Solidity 0.8+ reverts with a Panic(uint256) error code, which the Watch Tower does not recognize as a polling hint
• Failed external calls — If your handler calls another contract that reverts with its own custom error, those bytes propagate up and won’t match the known set
• Generic revert() or require(false) — These produce empty or non-standard revert data
• Out-of-gas in sub-calls — Can produce unexpected revert behavior

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Debugging steps

1. Reproduce the revert locally. Call getTradeableOrderWithSignature with the same parameters the Watch Tower uses (owner, params, offchainInput, proof) using cast call or a Foundry test:
   Copy

   Ask AI

   cast call <COMPOSABLE_COW> \
     "getTradeableOrderWithSignature(address,(address,bytes32,bytes),bytes,bytes32[])" \
     <OWNER> "(handler,salt,staticInput)" "0x" "[]" \
     --rpc-url <RPC_URL>
   
2. Inspect the revert data. If the call fails, check the raw revert bytes. Compare the first 4 bytes (the error selector) against the known selectors:
   • OrderNotValid: 0x16f2d3f3
   • PollTryNextBlock: 0x44882c68
   • PollTryAtBlock: 0x2d6e06d5
   • PollTryAtEpoch: 0x4184e129
3. Check for arithmetic edge cases. Review your handler for divisions that could hit zero denominators, multiplications that could overflow, or timestamp arithmetic that could underflow.
4. Run a local Watch Tower with --one-shot --only-owner <YOUR_SAFE> and LOG_LEVEL=DEBUG to see the exact error classification.

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Best practice: defensive error handling

function getTradeableOrder(
    address owner,
    address sender,
    bytes32 ctx,
    bytes calldata staticInput,
    bytes calldata offchainInput
) external view override returns (GPv2Order.Data memory order) {
    try this._getTradeableOrder(owner, sender, ctx, staticInput, offchainInput)
        returns (GPv2Order.Data memory result)
    {
        return result;
    } catch Error(string memory reason) {
        // Solidity require() / revert(string) — surface as OrderNotValid
        revert IConditionalOrder.OrderNotValid(reason);
    } catch (bytes memory) {
        // Panic, custom error from sub-call, or any other revert
        revert IConditionalOrder.OrderNotValid("unexpected internal error");
    }
}

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Salt and replay protection

• Use keccak256(abi.encodePacked(block.timestamp, nonce)) or similar for unique salts
• The salt is used to compute the order’s storage key in ComposableCoW
• Cancelling an order frees its salt for reuse

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Contract addresses (all chains)

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Related resources

• Setup Guide — Initial configuration walkthrough
• Architecture — How the system works
• Watch Tower — The service that monitors and posts programmatic orders
• Debugging Programmatic Orders — Decision tree for “why didn’t my order execute?”