How to Fix Uniswap Function Errors in Hardhat When Interacting with ETH

Discover how to easily resolve errors related to interactions with ETH in Uniswap functions using Hardhat, focusing on `swapExactETHForTokens` and `swapExactTokensForETH`. --- This video is based on the question https://stackoverflow.com/q/76750964/ asked by the user 'Eight' ( https://stackoverflow.com/u/11757196/ ) and on the answer https://stackoverflow.com/a/76762631/ provided by the user 'Ibrahim Khalil' ( https://stackoverflow.com/u/12497168/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Error when Interacting with ETH in Uniswap Functions (swapExactETHForTokens, swapExactTokensForETH) using Hardhat Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- Troubleshooting Uniswap Function Errors in Hardhat: A Guide If you're navigating the world of decentralized finance (DeFi) with Ethereum and interacting with Uniswap's smart contracts, you're likely to face some challenges. One such issue that many developers encounter involves errors when using UniswapV2 functions like swapExactETHForTokens and swapExactTokensForETH. In this post, we will delve into the common causes of these errors and how you can resolve them for smooth, efficient interaction with Uniswap via Hardhat. The Problem: Error While Using Uniswap Functions While attempting to execute functions that involve ETH transactions via Uniswap on Hardhat, a developer faced an error that stemmed from incorrect parameters passed into the contract functions. Specifically, the issue arose while trying to swap DAI tokens for ETH using the method swapExactTokensForETH. It was clear that the error was somehow linked to the parameters being passed to the function. Here’s a quick look at the error message received: [[See Video to Reveal this Text or Code Snippet]] This error hints at a fundamental issue: the data types for the addresses being used in the function calls were not set correctly. Let’s break down the solution to fix this problem. The Solution: Correctly Passing Contract Addresses In the context of the error message, the immediate issue relates to how we're passing the token addresses when invoking the function swapExactTokensForETH. Here's what we must consider and rectify: Understanding the Parameters The function swapExactTokensForETH is defined as follows in the smart contract: [[See Video to Reveal this Text or Code Snippet]] Here, the first parameter is tokenIn, which expects an Ethereum address as input—not the contract instance. How to Fix the Issue Identify the Token Address: Make sure you have the actual Ethereum address of the DAI token. You'll typically have it defined in your code as: [[See Video to Reveal this Text or Code Snippet]] Pass the Token Address: When you call the swapExactTokensForETH function, be sure to pass the DAI token address, not the contract instance. Update your test file as follows: [[See Video to Reveal this Text or Code Snippet]] By ensuring that you pass the token's Ethereum address correctly, you resolve the error about invalid addresses. Summary Tackling errors in smart contract interactions can be daunting, especially when dealing with decentralized exchanges and various token standards. In this guide, we discussed a common error encountered when calling Uniswap functions with Hardhat and provided a clear, actionable solution. The key takeaway is to ensure that you're passing the correct data types, in this case, the actual addresses instead of contract instances. By following the above steps, you should be well on your way to interacting with Uniswap functions without encountering invalid address errors. If you have further questions or encounter different issues, don’t hesitate to reach out for assistance—happy coding!