OpenZeppelin Hardhat Upgrades

Hardhat plugin for deploying and managing upgradeable contracts. This package adds functions to your Hardhat scripts so you can deploy and upgrade proxies for your contracts, whether you use ethers or viem.

⚠️ Migrating from Hardhat 2? See the Migration Guide for breaking changes and how to update your code, or see the example projects for complete transparent and UUPS proxy examples using Hardhat 3.

Installation

# install the plugin:
npm install --save-dev @openzeppelin/hardhat-upgrades

# and the peer dependencies for the library you use, either ethers:
npm install --save-dev @nomicfoundation/hardhat-ethers ethers

# or viem:
npm install --save-dev @nomicfoundation/hardhat-viem viem

Note: You need the @openzeppelin/hardhat-upgrades plugin plus the peer dependencies for the library you use: @nomicfoundation/hardhat-ethers and ethers, or @nomicfoundation/hardhat-viem and viem. (These are peer dependencies, so they aren't installed automatically.) If you use viem, import the plugin and the API from @openzeppelin/hardhat-upgrades/viem (not @openzeppelin/hardhat-upgrades); its functions take contract names and return viem contract instances. The examples below use ethers. See Usage with viem for the viem equivalents.

Register the @openzeppelin/hardhat-upgrades plugin in your hardhat.config.ts:

import { defineConfig } from 'hardhat/config';
import hardhatUpgrades from '@openzeppelin/hardhat-upgrades';

export default defineConfig({
  plugins: [hardhatUpgrades],
  // ... rest of config
});

As an alternative, you can import the plugin and the API from the @openzeppelin/hardhat-upgrades/ethers alias, which is equivalent to importing from @openzeppelin/hardhat-upgrades.

Usage in scripts

Important: Create a single network connection and share it across all operations. This ensures operations share the same context and state.

Proxies

You can use this plugin in a Hardhat script to deploy an upgradeable instance of one of your contracts via the deployProxy function:

// scripts/create-box.js
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades";

async function main() {
  // Create connection once and reuse for all operations
  const connection = await hre.network.create();
  const { ethers } = connection;
  const upgradesApi = await upgrades(hre, connection);
  
  const Box = await ethers.getContractFactory("Box");
  const box = await upgradesApi.deployProxy(Box, [42]);
  await box.waitForDeployment();
  console.log("Box deployed to:", await box.getAddress());
  
  // Reuse the same connection for upgrades
  const BoxV2 = await ethers.getContractFactory("BoxV2");
  await upgradesApi.upgradeProxy(await box.getAddress(), BoxV2);
}

main();

This will automatically check that the Box contract is upgrade-safe, deploy an implementation contract for the Box contract (unless there is one already from a previous deployment), create a proxy (along with a proxy admin if needed), and initialize it by calling initialize(42).

Then, in another script, you can use the upgradeProxy function to upgrade the deployed instance to a new version. The new version can be a different contract (such as BoxV2), or you can just modify the existing Box contract and recompile it - the plugin will note it changed.

// scripts/upgrade-box.js
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades";

async function main() {
  const connection = await hre.network.create();
  const { ethers } = connection;
  const upgradesApi = await upgrades(hre, connection);
  
  const BoxV2 = await ethers.getContractFactory("BoxV2");
  await upgradesApi.upgradeProxy(BOX_ADDRESS, BoxV2);
  console.log("Box upgraded");
}

main();

Note: While this plugin keeps track of all the implementation contracts you have deployed per network, in order to reuse them and validate storage compatibilities, it does not keep track of the proxies you have deployed. This means that you will need to manually keep track of each deployment address, to supply those to the upgrade function when needed.

The plugin will take care of comparing BoxV2 to the previous one to ensure they are compatible for the upgrade, deploy the new BoxV2 implementation contract (unless there is one already from a previous deployment), and upgrade the existing proxy to the new implementation.

Beacon proxies

You can also use this plugin to deploy an upgradeable beacon for your contract with the deployBeacon function, then deploy one or more beacon proxies that point to it by using the deployBeaconProxy function.

// scripts/create-box.js
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades";

async function main() {
  const connection = await hre.network.create();
  const { ethers } = connection;
  const upgradesApi = await upgrades(hre, connection);
  
  const Box = await ethers.getContractFactory("Box");

  const beacon = await upgradesApi.deployBeacon(Box);
  await beacon.waitForDeployment();
  console.log("Beacon deployed to:", await beacon.getAddress());

  const box = await upgradesApi.deployBeaconProxy(beacon, Box, [42]);
  await box.waitForDeployment();
  console.log("Box deployed to:", await box.getAddress());
}

main();

Then, in another script, you can use the upgradeBeacon function to upgrade the beacon to a new version. When the beacon is upgraded, all of the beacon proxies that point to it will use the new contract implementation.

// scripts/upgrade-box.js
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades";

async function main() {
  const connection = await hre.network.create();
  const { ethers } = connection;
  const upgradesApi = await upgrades(hre, connection);
  
  const BoxV2 = await ethers.getContractFactory("BoxV2");
  await upgradesApi.upgradeBeacon(BEACON_ADDRESS, BoxV2);
  console.log("Beacon upgraded");

  const box = BoxV2.attach(BOX_ADDRESS);
}

main();

Usage in tests

You can also use the plugin's functions from your Hardhat tests, in case you want to add tests for upgrading your contracts (which you should!). The API is the same as in scripts.

Important: Share a single connection across all tests in a suite. Create the connection once in a before block or use top-level await (ESM) to ensure all operations share the same context.

Proxies

import { expect } from "chai";
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades";

describe("Box", function() {
  let upgradesApi;
  let ethers;

  before(async () => {
    const connection = await hre.network.create();
    ({ ethers } = connection);
    upgradesApi = await upgrades(hre, connection);
  });

  it('works', async () => {
    const Box = await ethers.getContractFactory("Box");
    const BoxV2 = await ethers.getContractFactory("BoxV2");

    const instance = await upgradesApi.deployProxy(Box, [42]);
    const upgraded = await upgradesApi.upgradeProxy(await instance.getAddress(), BoxV2);

    const value = await upgraded.value();
    expect(value.toString()).to.equal('42');
  });
});

Beacon proxies

import { expect } from "chai";
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades";

describe("Box", function() {
  let upgradesApi;
  let ethers;

  before(async () => {
    const connection = await hre.network.create();
    ({ ethers } = connection);
    upgradesApi = await upgrades(hre, connection);
  });

  it('works', async () => {
    const Box = await ethers.getContractFactory("Box");
    const BoxV2 = await ethers.getContractFactory("BoxV2");

    const beacon = await upgradesApi.deployBeacon(Box);
    const instance = await upgradesApi.deployBeaconProxy(beacon, Box, [42]);
    
    await upgradesApi.upgradeBeacon(beacon, BoxV2);
    const upgraded = BoxV2.attach(await instance.getAddress());

    const value = await upgraded.value();
    expect(value.toString()).to.equal('42');
  });
});

Solidity tests

Hardhat 3 supports writing tests in Solidity. You can use Solidity to test deployments, upgrades, and upgrade safety via the @openzeppelin/foundry-upgrades Solidity library.

This is optional and only needed if you want Solidity-based tests.

Proxy source: In Solidity tests, proxies are compiled from the @openzeppelin/contracts version installed in your project (via proxyFilesToBuild() + Hardhat 3's npmFilesToBuild). In scripts and JavaScript/TypeScript tests, proxies come from precompiled bytecode bundled with the plugin. Because the two paths rely on independent sources and compilation settings, the resulting proxy bytecode may not be identical.

Install the library and forge-std:

npm install --save-dev @openzeppelin/foundry-upgrades "github:foundry-rs/forge-std#semver:^1.9.5"

Configure your Hardhat config for Solidity tests:

import { defineConfig } from 'hardhat/config';
import hardhatUpgrades, { proxyFilesToBuild } from '@openzeppelin/hardhat-upgrades';

if (!process.env.FOUNDRY_OUT) {
  process.env.FOUNDRY_OUT = 'artifacts/contracts';
}

export default defineConfig({
  plugins: [hardhatUpgrades],
  solidity: {
    version: '0.8.28',
    npmFilesToBuild: [...proxyFilesToBuild()],
  },
  test: {
    solidity: {
      ffi: true,
      fsPermissions: {
        readDirectory: ['artifacts/contracts'],
      },
    },
  },
});

Add a remappings.txt at your project root so the library's imports resolve to the npm package's source:

openzeppelin-foundry-upgrades/=node_modules/@openzeppelin/foundry-upgrades/src/

Write your Solidity tests using the Upgrades library, the same way you would in a Foundry project. The imports match the Foundry Upgrades API:

// test/MyContract.t.sol
import { Test } from "forge-std/Test.sol";
import { Upgrades } from "openzeppelin-foundry-upgrades/Upgrades.sol";

import { MyContract } from "../contracts/MyContract.sol";

contract MyContractTest is Test {
    function testDeploy() public {
        address proxy = Upgrades.deployTransparentProxy(
            "contracts/MyContract.sol:MyContract",
            msg.sender,
            abi.encodeCall(MyContract.initialize, (42))
        );

        assertEq(MyContract(proxy).value(), 42);
    }
}

Deploy and upgrade calls work the same as in a standalone Foundry project, including the upgrade safety checks that run automatically. See Using with Foundry for deploy and upgrade examples.

Run npx hardhat clean or npx hardhat compile --force before running your Solidity tests:

npx hardhat compile --force
npx hardhat test solidity

Usage with viem

If you use viem instead of ethers, import the plugin and the API from @openzeppelin/hardhat-upgrades/viem. It provides the same functions, but follows @nomicfoundation/hardhat-viem conventions: contracts are identified by their names (with autocompletion and typed results when artifact types have been generated by hardhat compile), addresses are typed as `0x${string}`, and the returned contract instances are viem contract instances with read and write functions.

Install the viem packages alongside this plugin:

npm install --save-dev @nomicfoundation/hardhat-viem viem

Register both plugins in your hardhat.config.ts, importing the upgrades plugin from @openzeppelin/hardhat-upgrades/viem so that your config type-checks without @nomicfoundation/hardhat-ethers installed:

import { defineConfig } from 'hardhat/config';
import hardhatViem from '@nomicfoundation/hardhat-viem';
import hardhatUpgrades from '@openzeppelin/hardhat-upgrades/viem';

export default defineConfig({
  plugins: [hardhatViem, hardhatUpgrades],
  // ... rest of config
});

Then use the upgrades factory function from @openzeppelin/hardhat-upgrades/viem:

// scripts/create-box.ts
import hre from "hardhat";
import { upgrades } from "@openzeppelin/hardhat-upgrades/viem";

async function main() {
  // Create connection once and reuse for all operations
  const connection = await hre.network.create();
  const upgradesApi = await upgrades(hre, connection);

  const box = await upgradesApi.deployProxy("Box", [42n]);
  console.log("Box deployed to:", box.address);
  console.log("Initial value:", await box.read.retrieve());

  // Reuse the same connection for upgrades
  const boxV2 = await upgradesApi.upgradeProxy(box.address, "BoxV2");
  await boxV2.write.increment();
}

main();

Beacons work the same way; the beacon instances returned by deployBeacon and upgradeBeacon are viem contract instances of the UpgradeableBeacon contract:

const beacon = await upgradesApi.deployBeacon("Box");
const box = await upgradesApi.deployBeaconProxy(beacon, "Box", [42n]);

await upgradesApi.upgradeBeacon(beacon, "BoxV2");
console.log("New implementation:", await beacon.read.implementation());

Functions that take options accept the same upgrade safety options, along with viem-style transaction options: client, gas, gasPrice, maxFeePerGas, maxPriorityFeePerGas, value, and libraries for contracts with external libraries. The client option is a { public, wallet } pair of viem clients. Its wallet client selects the account that signs the plugin's transactions and defaults to the first wallet client; it must be an account managed by the network connection, such as those from connection.viem.getWalletClients().

Inputs and outputs use viem types throughout, and this does not require ethers or @nomicfoundation/hardhat-ethers. See the BoxViem example project for a complete project.

Learn more

• Refer to the API documentation.
• Also see the main documentation for more info.