The Ultimate Guide to Debugging Smart Contracts: Tips and Tools for Web3 Developers
Tags: webdev, web3, beginners, javascript
Published: 2023-01-30 11:52:51

Smart contract development is vital to building decentralized applications on the blockchain. However, as with any software development, debugging smart contracts can be challenging but can quickly determine the cause of a single transaction or contract execution failure with an advanced tool for debugging Solidity smart contracts.

We can implement a suitable solution once we identify the kind of error that led to a specific issue and learn in-depth details about the error's nature.

This guide will provide tips and tools for debugging smart contracts to help web3 developers ensure their contracts are working as intended.

## Understanding Smart Contract Debugging

Smart contract debugging is identifying and fixing errors in smart contracts. It is essential in developing any decentralized application as it ensures that the contracts function as intended.

Smart contract development can run into several problems, including unpredictable behaviour, coding errors, and security flaws. Debugging can assist in resolving these problems and preventing more serious ones from developing later.

Writing, testing, and deployment are only a few of the processes involved in developing a smart contract. A crucial phase in each of these steps is debugging. After the contract is deployed, debugging helps find and correct flaws in the code introduced during the writing phase.

Debugging assists in finding and correcting issues that might have gone unnoticed during the writing stage during the testing phase. Debugging also ensures that the contract is deployed correctly and interacts with the blockchain as intended during deployment.

## Tips for Debugging Smart Contracts

Writing smart contracts that are easy to debug is a crucial step in development. Below are some tips for writing smart contracts that are easy to debug:

* Use simple, evocative names for your variables and functions so that anyone can quickly grasp what each one does and spot mistakes.
    
* Utilize the built-in solidity function called `require` to ensure that a particular condition is satisfied before the contract can continue executing. It's a valuable tool for debugging because it halts contract execution when the need is not met, enabling programmers to locate the problem fast.
    
* The [Truffle Debugger](https://trufflesuite.com/docs/truffle/how-to/debug-test/use-the-truffle-debugger/) is a powerful tool that can be used to debug smart contracts during the testing stage. It allows developers to step through the code, inspect variable values, and even revert to previous states.
    

![The Truffle Debugger](https://cdn.hashnode.com/res/hashnode/image/upload/v1674482687832/0cb03efa-4451-43f3-be4d-3cdd90bfa63d.png)

* The [remix](https://remix.ethereum.org/) is a well-liked online code editor for Solidity. It contains an integrated debugging function that enables programmers to browse the code and check the values of variables.
    

![Remix IDE](https://cdn.hashnode.com/res/hashnode/image/upload/v1674482824748/93ad34de-d99e-4186-b694-2d7ed8e07933.png)

## **Common Ethereum Smart Contract Error**

Syntax, Runtime, and logic errors are the most frequent problems engineers face while writing or running code for Solidity Smart Contracts.

### Syntax Error

A syntax error in a smart contract is a mistake in the code that prevents the computer from understanding it. Simple errors like omitting a semicolon or misusing a term can constitute a syntax fault.

### Logical Error

A logical error in a smart contract refers to a mistake in the code that doesn't prevent it from being executed but causes it to produce unexpected or incorrect results.

For instance, a smart contract transfers money to the incorrect address when sending money from one account to another.

An [audit](https://cointelegraph.com/blockchain-for-beginners/what-is-a-smart-contract-security-audit-a-beginners-guide) of a smart contract can find logical problems since, sometimes, from the developer's perspective, everything is going according to plan. Even though there might not be a bug in the code, an auditor can still execute a smart contract to look for security vulnerabilities, examine the business logic, and find loopholes.

### Runtime Error

Any error that takes place during the execution of a smart contract is referred to as a runtime error. This may occur if a contract fails to handle unexpected inputs or conditions correctly or attempts to carry out an operation prohibited by the underlying blockchain.

For instance, a contract that tries to transfer more money than is allowed in an account would result in a runtime error.

Runtime problems are more challenging to diagnose than syntax faults since they are not known before being deployed on a blockchain and can only occur when a smart contract's state changes.

## Common Ethereum Smart Contract Error Examples

### **Stack Overflow** **Errors**

In Solidity, a stack can only hold 1024 frames, meaning a function can only call itself 1024 times before a stack overflow happens. If there is an attempt to execute a function recursively and there is no condition to stop it, stack overflow will occur.

### **Stack Underflow** **Errors**

When there is an attempt to pop a nonexistent variable in assembly language, a stack underflow happens.

### **Execution Reverted** **Errors**

When a smart contract stops the execution of a transaction that deviates from its business logic, errors like this happen. Checks for various needed criteria are typically included in the Smart Contract code. The contract deems a transaction illegitimate and halts execution if even one requirement is not met.

It's vital to remember that a transaction will only be reverted if it was attempted to be completed but could not be executed based on the logic of the smart contract; in this case, the EVM will return an error, and the transaction will be reverted.

### **Out of gas** **Errors**

Out of gas error occurs when you don't provide enough gas to execute a transaction or gas is not enough to complete a transaction.

### **Invalid Opcode Errors**

The Invalid opcode errors occur when [EVM](https://ethereum.org/en/developers/docs/evm/) encounters an incompatibility with a Smart Contract. For instance, this happens when a compiler other than the one the network expected is used.

### **JUMP Errors**

The invalid `jump` happens when you try to call a function that doesn't exist, such as when you call a function of one contract through another contract that doesn't exist. A similar issue can happen when you use assembly language and point to false memory.

## Tools for Debugging Smart Contracts

In this previous section, we learn about common errors we may encounter in building and deploying smart contracts. Let's take a deep dive into the tools for debugging smart contracts.

### Hardhat

[Hardhat](https://hardhat.org/) is an open-source development environment for Ethereum. It includes tools for developing, testing, and deploying smart contracts. Hardhat also has a built-in debugger that allows developers to step through the code and inspect variable values.

![Hardhat](https://cdn.hashnode.com/res/hashnode/image/upload/v1674486756798/bf5d099a-3e36-4eb6-b50b-3689f11b9faa.png)

### Truffle

[Truffle](https://trufflesuite.com/) is a popular development framework for Ethereum. It includes a suite of tools for developing, testing, and deploying smart contracts. Truffle also consists of the Truffle Debugger, a powerful tool for debugging smart contracts during the testing stage.

![Trufflesuite](https://cdn.hashnode.com/res/hashnode/image/upload/v1674486811095/780174f9-9217-46d0-ae7d-86d7247c3db9.png)

### Remix

Remix is a popular online code editor for Solidity. It has a built-in debugging feature lets developers scan the code and inspect variable values.

![Remix IDE](https://cdn.hashnode.com/res/hashnode/image/upload/v1674487090252/8bf83951-f1ad-4d1f-b820-14282d4d6192.png)

### Etherscan

Etherscan is a blockchain explorer for Ethereum. It allows developers to inspect and debug smart contracts deployed on the Ethereum blockchain.

![Etherscan](https://cdn.hashnode.com/res/hashnode/image/upload/v1674487142081/89057d16-926c-44ac-9ec5-bac159e41ee9.png)

The stage of development and the project's particular requirements will determine the best tool to use for debugging smart contracts.

Remix and Etherscan are better suited for the deployment stage, whilst Truffle and Hardhat are better suited for testing. Truffle and Hardhat offer more sophisticated debugging tools, such as stepping code and returning to earlier states. Remix and Etherscan, on the other hand, provide additional visibility and transparency into the deployed contract.

It's crucial to test out various tools to determine which one best suits the demands of the project.

## Conclusion

Debugging smart contracts is a critical stage in creating decentralized apps for the blockchain. Web3 developers can ensure that their contracts operate as intended by following the advice and using the resources described in this guide.

As technology and best practices advance, it's critical to keep learning and experimenting with new tools and strategies for debugging smart contracts.

The documentation for Solidity, Truffle, and the Ethereum Stack Exchange are some more tools for learning and development.

## Resources

* [Ethereum Developers Tools list](https://github.com/ConsenSys/ethereum-developer-tools-list#developing-smart-contracts)
    
* [Smart Contract tools you need to know](https://betterprogramming.pub/top-10-smart-contract-developer-tools-you-need-for-2022-b763f5df689a)
    
* [Guide to Ethereum Developer Tools](https://www.myhsts.org/blog/ultimate-guide-to-ethereum-developer-tools.html)
    
* [How to Debug Smart Contract Transactions](https://medium.com/quillhash/how-to-debug-a-smart-contract-transaction-e76aa625c782)
    

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