I was following this article
but i stuck at upgrading contract an got this error
/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/hardhat/src/internal/core/providers/http.ts:78
const error = new ProviderError("HttpProviderError", -1);
^
ProviderError: Invalid params: invalid type: null, expected a 0x-prefixed hex string with length of 40.
at HttpProvider.request (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/hardhat/src/internal/core/providers/http.ts:78:19)
at LocalAccountsProvider.request (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/hardhat/src/internal/core/providers/accounts.ts:188:34)
at processTicksAndRejections (node:internal/process/task_queues:96:5)
at getStorageAt (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/@openzeppelin/upgrades-core/src/provider.ts:49:19)
at getStorageFallback (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/@openzeppelin/upgrades-core/src/eip-1967.ts:52:15)
at getAdminAddress (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/@openzeppelin/upgrades-core/src/eip-1967.ts:11:19)
at getUpgrader (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/@openzeppelin/hardhat-upgrades/src/upgrade-proxy.ts:42:26)
at Proxy.upgradeProxy (/Users/patarapichairat/Desktop/solidity/testupgrade/node_modules/@openzeppelin/hardhat-upgrades/src/upgrade-proxy.ts:27:23)
at main (/Users/patarapichairat/Desktop/solidity/testupgrade/scripts/upgradev2.js:8:2)
and this
Did i do something wrong? already search in google but not found. thank you