This is the code in my brownie.config.yaml file:

# exclude SafeMath when calculating test coverage
# https://eth-brownie.readthedocs.io/en/v1.10.3/config.html#exclude_paths
    - SafeMath
  - smartcontractkit/[email protected]
  - OpenZeppelin/[email protected]
      - '@chainlink=smartcontractkit/[email protected]'
      - '@openzeppelin=OpenZeppelin/[email protected]'
  from_key: ${PRIVATE_KEY}
  from_mnemonic: ${MNEMONIC} 

The error I receive when I try to run 'brownie run scripts/advanced_collectible/deploy_advanced.py":

brownie run scripts/advanced_collectible/deploy_advanced.py 
Brownie v1.14.3 - Python development framework for Ethereum

  File "brownie/_cli/__main__.py", line 64, in main
  File "brownie/_cli/run.py", line 38, in main
    if project.check_for_project():
  File "brownie/project/main.py", line 537, in check_for_project
    structure_config = _load_project_structure_config(folder)
  File "brownie/_config.py", line 243, in _load_project_structure_config
    data = _load_config(project_path).get("project_structure", {})
  File "brownie/_config.py", line 180, in _load_config
    return yaml.safe_load(fp)
  File "yaml/__init__.py", line 162, in safe_load
    return load(stream, SafeLoader)
  File "yaml/__init__.py", line 114, in load
    return loader.get_single_data()
  File "yaml/constructor.py", line 49, in get_single_data
    node = self.get_single_node()
  File "yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "yaml/composer.py", line 127, in compose_mapping_node
    while not self.check_event(MappingEndEvent):
  File "yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "yaml/parser.py", line 438, in parse_block_mapping_key
    raise ParserError("while parsing a block mapping", self.marks[-1],
ParserError: while parsing a block mapping
  in "/Users/zeeshanbhatti/Desktop/nftDemo/brownie-config.yaml", line 3, column 1
expected <block end>, but found '<block mapping start>'
  in "/Users/zeeshanbhatti/Desktop/nftDemo/brownie-config.yaml", line 15, column 2

Any advice and background information on what this means would be much appreciated!

  • So odd... did you git clone to start this? May 6, 2021 at 23:16
  • No, I was just following along with your video and looking at the git to make sure i was on the right path. Should i try to git clone it?
    – rizonpoint
    May 6, 2021 at 23:28
  • Hmmm, if you hit clone the repo you probably won’t run into the errors.... but it can also be good to code along May 7, 2021 at 2:15
  • What’s on line 15 and line 3 of your config? May 7, 2021 at 2:15
  • 1
    Maybe add dotenv: .env to the file? Perhaps you don’t have the environment variables set May 7, 2021 at 2:17

2 Answers 2



dotenv: .env

To your brownie-config.yaml. It’s not picking up your environment variables, and this forces brownie to pick them up out of your .env file.


I was also getting the following error

    ParserError: while parsing a block mapping
      in "/Users/sm/demos/brownie_fund_me/brownie- 
    config.yaml", line 10, column 2
    expected <block end>, but found '<block mapping 
      in "/Users/sm/demos/brownie_fund_me/brownie- 
    config.yaml", line 13, column 3

For me the issue was with yaml format, I changed the line no. 13 indentation and it worked

Would suggest to use yaml formatter for all yaml files

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