I'm using this program to make an NFT https://github.com/PatrickAlphaC/nft-mix and I get this error when I run create_collectable.py

File "brownie/_cli/run.py", line 50, in main
    return_value, frame = run(
  File "brownie/project/scripts.py", line 103, in run
    return_value = f_locals[method_name](*args, **kwargs)
  File "./scripts/rizer_incept/create_incept.py", line 10, in main
    fund_with_link(rizer_incept.address, "as_proxy_for")
  File "./scripts/helpful_scripts.py", line 40, in fund_with_link
    tx = interface.LinkTokenInterface(link_token).transfer(
  File "brownie/network/contract.py", line 615, in __call__
    return Contract.from_abi(self._name, address, self.abi, owner)
  File "brownie/network/contract.py", line 929, in from_abi
    address = _resolve_address(address)
  File "brownie/network/web3.py", line 193, in _resolve_address
    return to_address(domain)
  File "brownie/convert/main.py", line 43, in to_address
    return str(EthAddress(value))
  File "brownie/convert/datatypes.py", line 204, in __new__
    raise ValueError(f"'{value}' is not a valid ETH address") from None
ValueError: 'None' is not a valid ETH address

I think that the error has something to do with

tx = interface.LinkTokenInterface(link_token).transfer(
        contract_address, amount, {"from": account}

aka line 40 in helpful_scripts.py

I think it has something to do with the fact that account=None. How should I set account to avoid this error?

2 Answers 2


Without just hardcoding your private key into the script you are running, you'll have to set your private key as an environment variable with $ export PRIVATE_KEY=<PRIVATE_KEY>. In your context, the account in create_collectable.py is instantiated from brownie-config which reads in your private key from .env. To set the environment variables from your .env run $ source .env in the same directory.

  • 1
    This is good but the problem was actually the chainlink address. The variable link_token was actually never set, and it should be the chainlink token's contract address. I'm assuming because the repo set link_token to None you're probably supposed to set this variable in your env file or something like that. Nov 3, 2021 at 1:59

I figured out what the problem was. You have to actually put the chainlink token address into the variable link_token so lines 84 to 86 in /scripts/helpful_scripts.py currently look like this:

def fund_with_link(
    contract_address, account=None, link_token=None, amount=1000000000000000000

But that function is supposed to look like this:

def fund_with_link(
    contract_address, account=None, link_token="0x01BE23585060835E02B77ef475b0Cc51aA1e0709", amount=1000000000000000000

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