TX goes through but FallbackProvider throws 'already known' or 'nonce too low' error

[chicken-juju]

Ethers Version

6.6.2

Search Terms

provider

Describe the Problem

My provider is configured as follows

export const provider = new ethers.FallbackProvider([
  {
    provider: new ethers.JsonRpcProvider(process.env.NODE_URL_1),
    priority: 1,
    weight: 2
  },
  {
    provider: new ethers.JsonRpcProvider(process.env.NODE_URL_2),
    priority: 2,
    weight: 2
  },
  {
    provider: new ethers.JsonRpcProvider(process.env.NODE_URL_3),
    priority: 3,
    weight: 2
  }
])

When making a smart contract call await contractName.something() the TX succeeds on the explorer but ethers throws one of these errors-

Feed update failed Error: nonce has already been used (transaction="0x02f8b5820fa2830468d8843b9aca0084b2d05e0083030d409428e449afc8a04ed97ca840aa83b64c7c1f5f55ad80b84417835d1c000000000000000000000000000000000000000000000000000000000004809900000000000000000000000000000000000000000000000000000000649d5023c080a0b6c47a90cdae1b294a9349db737ab282ce77b9c201777efaa6b8c0446e0156c9a04d5a1d45dc73d4017e688797e583c232ca1382e1ecdfbf0377578282862cbf44", info={ "error": { "code": -32000, "message": "nonce too low" } }, code=NONCE_EXPIRED, version=6.6.2)
    at makeError (/home/hp/Documents/voodoo/voodoo-keeper-server/node_modules/ethers/src.ts/utils/errors.ts:677:21)
    at JsonRpcProvider.getRpcError (/home/hp/Documents/voodoo/voodoo-keeper-server/node_modules/ethers/src.ts/providers/provider-jsonrpc.ts:949:33)
    at /home/hp/Documents/voodoo/voodoo-keeper-server/node_modules/ethers/src.ts/providers/provider-jsonrpc.ts:524:45
    at processTicksAndRejections (node:internal/process/task_queues:95:5) {
  code: 'NONCE_EXPIRED',
  transaction: '0x02f8b5820fa2830468d8843b9aca0084b2d05e0083030d409428e449afc8a04ed97ca840aa83b64c7c1f5f55ad80b84417835d1c000000000000000000000000000000000000000000000000000000000004809900000000000000000000000000000000000000000000000000000000649d5023c080a0b6c47a90cdae1b294a9349db737ab282ce77b9c201777efaa6b8c0446e0156c9a04d5a1d45dc73d4017e688797e583c232ca1382e1ecdfbf0377578282862cbf44',
  info: { error: { code: -32000, message: 'nonce too low' } }
}

Feed update failed Error: could not coalesce error (error={ "code": -32000, "message": "already known" }, payload={ "id": 37, "jsonrpc": "2.0", "method": "eth_sendRawTransaction", "params": [ "0x02f8b5820fa2830468db843b9aca0084b2d05e0083030d409428e449afc8a04ed97ca840aa83b64c7c1f5f55ad80b84417835d1c00000000000000000000000000000000000000000000000000000000000480ee00000000000000000000000000000000000000000000000000000000649d50a1c080a08d69aa7c4989adaf2ae58f5f44d08ce7adb4a614b9fd02e26c4dde547a925d57a06f99a70f002bf589df028b26ccf6abf3f554da8feaa8e594b5f72e52a31ff7d8" ] }, code=UNKNOWN_ERROR, version=6.6.2)
    at makeError (/home/hp/Documents/voodoo/voodoo-keeper-server/node_modules/ethers/src.ts/utils/errors.ts:677:21)
    at JsonRpcProvider.getRpcError (/home/hp/Documents/voodoo/voodoo-keeper-server/node_modules/ethers/src.ts/providers/provider-jsonrpc.ts:977:25)
    at /home/hp/Documents/voodoo/voodoo-keeper-server/node_modules/ethers/src.ts/providers/provider-jsonrpc.ts:524:45
    at processTicksAndRejections (node:internal/process/task_queues:95:5) {
  code: 'UNKNOWN_ERROR',
  error: { code: -32000, message: 'already known' },
  payload: {
    method: 'eth_sendRawTransaction',
    params: [
      '0x02f8b5820fa2830468db843b9aca0084b2d05e0083030d409428e449afc8a04ed97ca840aa83b64c7c1f5f55ad80b84417835d1c00000000000000000000000000000000000000000000000000000000000480ee00000000000000000000000000000000000000000000000000000000649d50a1c080a08d69aa7c4989adaf2ae58f5f44d08ce7adb4a614b9fd02e26c4dde547a925d57a06f99a70f002bf589df028b26ccf6abf3f554da8feaa8e594b5f72e52a31ff7d8'
    ],
    id: 37,
    jsonrpc: '2.0'
  }
}

One reason could be that Ethers calls eth_sendRawTransaction on multiple RPC servers. The first TX succeeds and the duplicates fail. Some context about our setup. We want to run one JsonRpcProvider at a time. The others are for redundancy and are therefore have different priorities. The errors are not thrown if we leave a single RPC and comment out the rest.

Code Snippet

No response

Contract ABI

No response

Errors

No response

Environment

Ethereum (mainnet/ropsten/rinkeby/goerli), Altcoin - Please specify (e.g. Polygon), node.js (v12 or newer)

Environment (Other)

Fantom testnet

[ricmoo]

This has been fixed in 6.9.0.

Let me know if you still get any weird behaviour. I've also added a flexible FallbackProvider-based test suite to make it easy to add more tests for expected FallbackProvider behaviour.

Thanks! :)