# \[Archive\] Send your first transaction with ERC-20 Paymaster | Web3Auth **URL:** \ **Category:** Embedded Wallets (Web3Auth)\ **Created:** [October 30, 2024, 6:53am UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029 "2024-10-30T06:53:30Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![shahbaz](https://yyz1.discourse-cdn.com/flex011/user_avatar/builder.metamask.io/shahbaz/32/1527_2.png) [@shahbaz](https://builder.metamask.io/u/shahbaz)\ **Post date:** [October 30, 2024, 6:53am UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/1 "2024-10-30T06:53:30Z")
> **🏛 Archived Content from Web3Auth Community** > > This topic was originally posted by **shahbaz** on 10/30/2024. > This content has been migrated from our previous community forum to preserve valuable discussions. * * * A paymaster is a vital component in the ERC-4337 standard, responsible for covering transaction costs on behalf of the user. There are various types of paymasters, such as gasless paymasters, ERC-20 paymasters, and more. * * * This is a companion discussion topic for the original entry at [https://web3auth.io/docs/guides/erc20-paymaster](https://web3auth.io/docs/guides/erc20-paymaster) ---
**Author:** ![pratikraj.bhavsar](https://avatars.discourse-cdn.com/v4/letter/p/76d3ee/32.png) [@pratikraj.bhavsar](https://builder.metamask.io/u/pratikraj.bhavsar)\ **Post date:** [May 15, 2025, 10:02pm UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/2 "2025-05-15T22:02:53Z")
Hello, I tried exactly your tutorial but it does not work I created a new project from the [quickstart](https://web3auth.io/docs/quick-start?product=PNP&sdk=PNP_MODAL&framework=REACT&stepIndex=0) then follow this for send usdc and got the following error : Unhandled Promise Rejection: UserOperationExecutionError: Paymaster `postOp` function reverted. and on Pimlico I see this error { “id”: 12, “error”: { “code”: -32521, “message”: “UserOperation reverted during simulation with reason: AA50 postOp reverted 0x7939f424” }, “jsonrpc”: “2.0” } I have generated a debug link on tenderly ![](https://canada1.discourse-cdn.com/flex011/uploads/metamaskbuilderhub/original/1X/cddbc8c95529eb8f355a5d1edf59fcbf65e0d3c4.png) ``` dashboard.tenderly.co ``` ![](https://canada1.discourse-cdn.com/flex011/uploads/metamaskbuilderhub/original/1X/aa2181d272692e34cdf1236f251893fd5ab0cdf3.png) ### [Tenderly Dashboard](https://dashboard.tenderly.co/shared/simulation/993207d6-b149-42ad-a9a7-34f773168c8e) Tenderly is a full-stack infrastructure for the entire dapp lifecycle, offering the only node RPC with built-in development environments and tools. Sign up now! I am stuck on this for a few months and losing my hair. Could you help me ? Thanks, Pratik ---
**Author:** ![shahbaz](https://yyz1.discourse-cdn.com/flex011/user_avatar/builder.metamask.io/shahbaz/32/1527_2.png) [@shahbaz](https://builder.metamask.io/u/shahbaz)\ **Post date:** [May 15, 2025, 10:02pm UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/3 "2025-05-15T22:02:53Z")
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**Author:** ![Ayush](https://yyz1.discourse-cdn.com/flex011/user_avatar/builder.metamask.io/ayush/32/1540_2.png) [@Ayush](https://builder.metamask.io/u/Ayush)\ **Post date:** [May 20, 2025, 1:42pm UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/4 "2025-05-20T13:42:48Z")
Hey @pratikraj.bhavsar can you please share the code for AccountAbstractionProvider. We’ll need more details to debug the issue. ---
**Author:** ![pratikraj.bhavsar](https://avatars.discourse-cdn.com/v4/letter/p/76d3ee/32.png) [@pratikraj.bhavsar](https://builder.metamask.io/u/pratikraj.bhavsar)\ **Post date:** [May 20, 2025, 3:34pm UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/5 "2025-05-20T15:34:27Z")
> //Blockquote > const accountAbstractionProvider = new AccountAbstractionProvider({ > config: { > chainConfig, > bundlerConfig: { > // Get the pimlico API Key from [dashboard.pimlico.io](http://dashboard.pimlico.io) > url: `https://api.pimlico.io/v2/${chainId}/rpc?apikey=${pimlicoAPIKey}`, > paymasterContext: { > // USDC address on Ethereum Sepolia > token: “0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238”, > }, > }, > smartAccountInit: new SafeSmartAccount(), > paymasterConfig: { > // Get the pimlico API Key from [dashboard.pimlico.io](http://dashboard.pimlico.io) > url: `https://api.pimlico.io/v2/${chainId}/rpc?apikey=${pimlicoAPIKey}`, > }, > }, > }); > //Blockquote > // IMP START - SDK Initialization > const privateKeyProvider = new EthereumPrivateKeyProvider({ > config: { chainConfig }, > }); > //Blockquote > const web3AuthOptions: Web3AuthOptions = { > clientId, > web3AuthNetwork: WEB3AUTH\_NETWORK.SAPPHIRE\_DEVNET, > privateKeyProvider, > // Use the account abstraction provider we configured earlier > accountAbstractionProvider, > // This will allow you to use EthereumPrivateKeyProvider for > // external wallets, while use the AccountAbstractionProvider > // for Web3Auth embedded wallets. > useAAWithExternalWallet: false, > }; > const web3auth = new Web3Auth(web3AuthOptions); then I send the transaction > // Use the same accountAbstractionProvider we created earlier. > const bundlerClient = accountAbstractionProvider.bundlerClient!; > const smartAccount = accountAbstractionProvider.smartAccount!; > > // Pimlico’s ERC-20 Paymaster address > const pimlicoPaymasterAddress = “0x0000000000000039cd5e8aE05257CE51C473ddd1”; > > // USDC address on Ethereum Sepolia > const usdcAddress = “0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238”; > > // 0.00001 ETH in WEI format > const amount = 10000000000000n; > > // 10 USDC in WEI format. Since USDC has 6 decimals, 10 \* 10^6 > const approvalAmount = 1000000n; > > const userOpHash = await bundlerClient.sendUserOperation({ > account: smartAccount, > calls: [ > // Approve USDC on Sepolia chain for Pimlico’s ERC 20 Paymaster > { > to: usdcAddress, > abi: parseAbi([“function approve(address,uint)”]), > functionName: “approve”, > args: [pimlicoPaymasterAddress, approvalAmount], > }, > { > to: “0xf63d71b8E48AAdbdcf49bfF0CB849eC98efc4849”, > value: amount, > data: “0x”, > }, > { > to: “0xf63d71b8E48AAdbdcf49bfF0CB849eC98efc4849”, > value: amount, > data: “0x”, > }, > ], > }); > > // Retrieve user operation receipt > const receipt = await bundlerClient.waitForUserOperationReceipt({ > hash: userOpHash, > }); ---
**Author:** ![Ayush](https://yyz1.discourse-cdn.com/flex011/user_avatar/builder.metamask.io/ayush/32/1540_2.png) [@Ayush](https://builder.metamask.io/u/Ayush)\ **Post date:** [May 21, 2025, 1:46am UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/6 "2025-05-21T01:46:13Z")
Looks like Pimlico’s paymaster address is changed, can you change the `pimlicoPaymasterAddress` to `0x777777777777AeC03fd955926DbF81597e66834C` and try once? ---
**Author:** ![pratikraj.bhavsar](https://avatars.discourse-cdn.com/v4/letter/p/76d3ee/32.png) [@pratikraj.bhavsar](https://builder.metamask.io/u/pratikraj.bhavsar)\ **Post date:** [May 21, 2025, 5:30pm UTC](https://builder.metamask.io/t/archive-send-your-first-transaction-with-erc-20-paymaster-web3auth/1029/7 "2025-05-21T17:30:39Z")
Hello, it’s working thank you very much. I am trying to send 1 USDC Could you tell me what value should I put in const amount = ?; // 10 USDC in WEI format. Since USDC has 6 decimals, 10 \* 10^6 const approvalAmount = ?; Regards, Pratik