I try to connect to mumbai testnet in javascript. I don't want to use alchemy, infura or something like this, but want to connect drectly. I already have deployed a smart contract to mumbai-testnet.

I try the following:

const provider = new ethers.providers.JsonRpcProvider(process.env.URL);

where my Url in the .env file is:


everything works so far, I even get access to my wallet using:

const wallet = new ethers.Wallet(private_key, provider)

now I am connecting my smart contract like this:

const contract = new ethers.Contract(deployed_contact_address, abi, provider);

I think this also works so far, if I use console.log to show the contract, I can see the functions included in smart contract. But if I want to access the functions like this:

var out_min = contract.getAmountOutMin(dict_routers.get("uniswap_v2"), dict_bA.get("MATIC"), dict_tok.get("DAI"), 100);

I get an error:

        var error = new Error(message);

Error: network does not support ENS (operation="getResolver", network="maticmum", code=UNSUPPORTED_OPERATION, version=providers/5.6.8)
    at Logger.makeError (C:\Users\danis\arbitrage_bot\node_modules\@ethersproject\logger\lib\index.js:233:21)
    at Logger.throwError (C:\Users\danis\arbitrage_bot\node_modules\@ethersproject\logger\lib\index.js:242:20)
    at JsonRpcProvider.<anonymous> (C:\Users\danis\arbitrage_bot\node_modules\@ethersproject\providers\lib\base-provider.js:2305:36)
    at step (C:\Users\danis\arbitrage_bot\node_modules\@ethersproject\providers\lib\base-provider.js:48:23)
    at Object.next (C:\Users\danis\arbitrage_bot\node_modules\@ethersproject\providers\lib\base-provider.js:29:53)
    at fulfilled (C:\Users\danis\arbitrage_bot\node_modules\@ethersproject\providers\lib\base-provider.js:20:58)
    at processTicksAndRejections (node:internal/process/task_queues:96:5) {
  reason: 'network does not support ENS',
  operation: 'getResolver',
  network: 'maticmum'

Can someone tell me, what is going wrong here? I don't know what to do anymore. Thank you!

  • Without knowing the contract you are calling and what your input looks like, it is very hard to tell. I would guess that one of the addresses has an incorrect format (should be an address, but is a string) and thus is interpreted as ENS Aug 16, 2022 at 20:27
  • Thanks for your answer. How can I check this? How can I change the string to an address?
    – Dani S
    Aug 16, 2022 at 21:03

2 Answers 2


Your address is coming up as a string. To try a fix, just paste the address (e.g. "0x12345..." into the field where the variable name is

If that's your issue, its just a javascript issue on reading the env/variable correctly

  • I replaced all variable names with the addresses, but it is still not working
    – Dani S
    Aug 17, 2022 at 14:27
  • are the addresses in quotes?
    – thefett
    Aug 17, 2022 at 14:54
  • I tried with quotes and without quotes
    – Dani S
    Aug 17, 2022 at 15:55

If you want to write to the smart contract you have to sign it with a signer argument..hope it will help.

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