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Troubleshooting Guide

This guide provides solutions to common issues you might encounter when developing with VIA Labs' cross-chain messaging system.

Deployment Issues#

Contract Deployment Fails#

Symptoms: Contract deployment transaction reverts or fails.

Possible Causes and Solutions:

  1. Insufficient Gas:

    • Ensure you have enough native tokens for gas fees.
    • Try increasing the gas limit for your deployment transaction.

  2. Constructor Arguments:

    • Verify that you're providing the correct arguments to your contract's constructor.
    • Check the data types and formats of your constructor arguments.

  3. Contract Size Limit:

    • Your contract might exceed the maximum contract size limit (24KB).
    • Consider refactoring your contract to reduce its size, or split it into multiple contracts.

Configuration Issues#

Chain Configuration Fails#

Symptoms: The configureClient() function reverts or fails.

Possible Causes and Solutions:

  1. Invalid Message Contract Address:

    • Ensure you're using the correct VIA Gateway Contract address for each chain.
    • Verify the addresses in the Supported Networks page.

  2. Incorrect Chain IDs:

    • Verify that you're using the correct chain IDs for the networks you're configuring.
    • Check the chain IDs in the Supported Networks page.

  3. Duplicate Chain IDs:

    • Ensure you're not trying to configure the same chain ID multiple times.
    • Check your chain ID array for duplicates.

"onlyActiveChain" Error#

Symptoms: Transactions revert with an "onlyActiveChain" error.

Possible Causes and Solutions:

  1. Chain Not Configured:

    • The destination chain hasn't been configured in your contract.
    • Call configureClient() to configure all chains you intend to communicate with.

  2. Incorrect Chain ID:

    • You might be using an incorrect chain ID when sending messages.
    • Verify the chain ID against the Supported Networks page.

Message Sending Issues#

Message Sending Fails#

Symptoms: The _sendMessage() function reverts or fails.

Possible Causes and Solutions:

  1. Insufficient Gas:

    • Ensure you have enough native tokens for gas fees.
    • Try increasing the gas limit for your transaction.

  2. Chain Not Active:

    • The destination chain might not be configured or active.
    • Verify that you've properly configured the destination chain using configureClient().

  3. Message Too Large:

    • Your message might be too large, exceeding gas limits.
    • Try reducing the size of your message or splitting it into multiple smaller messages.

Message Reception Issues#

Messages Not Being Received#

Symptoms: Messages are sent successfully but not received on the destination chain.

Possible Causes and Solutions:

  1. Implementation Error:

    • Ensure you've correctly implemented the _processMessage() function in your contract.
    • Check for any errors in your message decoding logic.

  2. Network Congestion:

    • During periods of high network congestion, message delivery might be delayed.
    • Wait for the network congestion to clear, or consider using a different chain.

  3. Contract Address Mismatch:

    • Ensure that the contract addresses are correctly configured on both chains.
    • Verify that you're using the same contract implementation on both chains.

Message Processing Errors#

Symptoms: Messages are received but not processed correctly.

Possible Causes and Solutions:

  1. Decoding Errors:

    • Ensure you're using the correct data types and format when decoding messages.
    • Verify that the encoding on the source chain matches the decoding on the destination chain.

  2. Logic Errors:

    • Check your message processing logic for any errors or edge cases.
    • Add logging to help debug the issue.

  3. State Inconsistencies:

    • The state of your contract on the destination chain might be inconsistent with the source chain.
    • Implement mechanisms to handle state synchronization between chains.

Debugging Techniques#

Using Console.log for Debugging#

OpenZeppelin provides a helpful console.log utility that allows you to print debug information to your development environment. This is extremely useful for debugging cross-chain applications.

First, import the console library in your contract:

// SPDX-License-Identifier: MITpragma solidity ^0.8.9;
import "@openzeppelin/contracts/utils/Strings.sol";import "hardhat/console.sol";
contract MyContract is MessageClient {    // Your contract code}

Then, you can use console.log to output debug information:

function _processMessage(uint _txId, uint _sourceChainId, bytes calldata _data) internal override {    // Log the source chain ID    console.log("Message received from chain:", _sourceChainId);        // Log the transaction ID    console.log("Transaction ID:", _txId);        // Log the data length    console.log("Data length:", _data.length);        // Decode and process the message    (address recipient, uint amount) = abi.decode(_data, (address, uint));        // Log the decoded values    console.log("Recipient:", Strings.toHexString(uint160(recipient), 20));    console.log("Amount:", amount);        // Process the message    // ...}

Note: console.log only works in development environments like Hardhat and Foundry. It will not work on public networks, but the code will still be valid and will simply be ignored on mainnet.

Testing on Testnets#

Always test your cross-chain applications thoroughly on testnets before deploying to mainnet:

  1. Start Small: Begin with simple message passing between two chains.
  2. Incremental Testing: Gradually add complexity to your tests.
  3. Edge Cases: Test edge cases and error conditions to ensure your application handles them correctly.
  4. Multiple Chains: Test with multiple chains to ensure your application works across all supported networks.

Getting Help#

If you're still experiencing issues after trying the solutions in this guide:

  1. Check the FAQ: Our FAQ might have answers to your questions.
  2. Join Our Discord: Connect with the VIA Labs community on Discord.
  3. Contact Support: Reach out to our support team at support@vialabs.io.
  4. GitHub Issues: Check for known issues or report new ones on our GitHub repository.