connecting to local substrate-contracts-node with polkadotjs api

Question

I'm running the substrate-contracts-node 0.40.0-17065f31ac4 with the command

./artifacts/substrate-contracts-node-linux/substrate-contracts-node --log info,runtime::contracts=debug

, and am trying to connect to it over websocket from a js/ts script using polkadotjs api:

const wsProvider = new WsProvider('ws://127.0.0.1:9944');
const api = await ApiPromise.create({ provider: wsProvider });

But I get this error:

node:internal/event_target:1096
  process.nextTick(() => { throw err; });
                           ^

TypeError: Cannot read properties of null (reading 'length')
    at WebSocket.__internal__onSocketMessage (file:///home/dotdev/gits/accounts_setup/node_modules/@polkadot/rpc-provider/ws/index.js:393:40)
    at [nodejs.internal.kHybridDispatch] (node:internal/event_target:822:20)
    at WebSocket.dispatchEvent (node:internal/event_target:757:26)
    at fireEvent (node:internal/deps/undici/undici:10978:14)
    at websocketMessageReceived (node:internal/deps/undici/undici:11000:7)

The length property is read in polkadotjs at this line:

        const bytesRecv = message.data.length;

When I'm connection with polkadotjs ui to my local node, it works fine though (I checked it's using the same endpoint as my script).

The contracts IU at https://ui.use.ink/?rpc=ws://127.0.0.1:9944 also doesn't complain.

The complete script is in the file index.ts:

import { ApiPromise, WsProvider, Keyring } from '@polkadot/api';
const wsProvider = new WsProvider('ws://127.0.0.1:9944');
const api = await ApiPromise.create({ provider: wsProvider });
console.log(api.genesisHash.toHex());
await api.disconnect()

And I run it with esrun index.ts.

What am I doing wrong?

Answer 1

This was due to this project using node 22. Switching back to node 21.7.3 made it work fine.

Note that changing the WsProvider to a public node like rpc.polkadot.io actually gave the same problems. The problem was unrelated to substrate-contracts-node, and only due to the node version used.