Ethereum: Missing revert data (Hardhat/Ganache)

Missing Revert Data: A Potential Bug in Ethereum Hardhat and Ganache

Ethereum, like any other blockchain platform, is not immune to bugs. In the context of Hardhat, a popular development environment for Ethereum smart contracts, missing revert data can occur. This error occurs when the contract tries to revert an invalid opcode but cannot retrieve the required revert data.

The Problem: Missing Revert Data

When a transaction in an Ethereum smart contract goes wrong, the contract’s execution engine throws an exception. In this case, the exception is usually a “RuntimeError” due to a virtual machine (VM) error. The error message usually indicates that the VM encountered an invalid opcode. However, sometimes the underlying problem can be more complex and require additional data.

Hardhat and Ganache: The Environment

Hardhat is a development environment designed for developing Ethereum smart contracts using Solidity. It is based on Web3.js and provides tools like Ganache for testing contracts locally without deploying them to the mainnet. When using Hardhat or Ganache, you rely on their internal state management systems to maintain the virtual machine.

The problem: Missing revert data in Hardhat/Ganache

In Hardhat and Ganache, missing revert data is particularly problematic because it can cause unexpected behavior or errors when trying to recover a contract’s execution. The “revertData” field of the error object can be empty or null, indicating that the contract failed to obtain the required revert data.

Example Error

Here is an example of what the error message might look like:

{
"error": {
"message": "VM exception processing transaction: invalid opcode",
"stack": [
"RuntimeError: VM exception processing opcode at index 0 of [0x...]"
]
},
"info": {
"dataRevert": null // or empty string
}
}

In this case, the contract attempted to undo an invalid opcode, but was unable to obtain the required undo data (dataRevert).

Troubleshooting

To troubleshoot missing undo data errors in Hardhat and Ganache:

• Check your error messages: Check the stack trace to determine which opcode is causing the problem.

• Check contract status: Make sure the internal state of the contract is correct before attempting to revert an invalid opcode.

• Use revertData field

  

  : Check that the revertData field is present and not empty. If it is, update your code to retrieve the required undo data.

Best Practices

How to minimize errors when working with missing undo data:

• Test in local environments: Use Hardhat or Ganache locally before deploying contracts to mainnet.

• Use revertData field: Always check that the dataRevert field is populated and update your code accordingly.

By being aware of the potential issue of missing undo data, developers can take steps to prevent and fix this error, ensuring more reliable and maintainable smart contract development in Ethereum environments such as Hardhat and Ganache.