unsupported getDefaultProvider network

[ripcordChain]

Hi!
I try to test my code for Polygon network on the testnet Mumbai.
When I change my settings from Kovan to Mumbai using Infura, I face this error message : “unsupported getDefaultProvider network”.
No problem on Kovan, it works as I expect to.

import { ethers } from "ethers";
const fs = require("fs");
const mnemonic = fs.readFileSync(".secretMnemo").toString().trim();
let path = "m/44'/60'/0'/0/1";
const wallet = ethers.Wallet.fromMnemonic(mnemonic, path);
const infuraKeyMumbai = fs.readFileSync(".secretInfuraKeyMumbai").toString().trim();
const provider = ethers.getDefaultProvider('mumbai', {
    infura: "https://polygon-mumbai.infura.io/v3/" + infuraKeyMumbai
}); 

Error :

reason: ‘unsupported getDefaultProvider network’,
code: ‘NETWORK_ERROR’,
operation: ‘getDefaultProvider’,
network: ‘mumbai’

Ethers.js version : 5.4.6

Do you know what can be the problem ?
Thanks for your help!

[ricmoo]

The default provider does not currently support Mumbai. I am waiting on a billing issue with INFURA, and then I should be able to add it.

For now the easiest thing to do is either register with INFURA for your own polygon-enabled account and use the InfuraProvider or to use the AlchemyProvider (which will work best if you register for your own API key, but Alchemy does provide polygon support on the ethers-provided keys).

[ripcordChain]

Many thanks Richard!
I will try these solutions.