PyYAML error: "yaml.scanner.ScannerError: mapping values are not allowed here"

Question

I'm getting a strange error when parsing a YAML:

yaml.scanner.ScannerError: mapping values are not allowed here

The YAML file I'm trying to read is valid according to YAML Lint

Another strange thing is that it works fine on my laptop (Arch Linux) but not on the Server (Ubuntu). The PyYAML version is the same though on both machines.

I have seen the other posts on stackoverflow where people were missing the space after the colon, but I'm not missing any spaces.

This is the complete YAML file:

pipeline:
    - read:
            input: /home/omnibrain/projects/company/data/data.csv
            output: some_data
    - filter:
            input: some_data
            filtername: latlng_filter
            minlat: 32.5
            maxlat: 32.9
            minlng: -117.4
            maxlng: -117.0
    - enhance:
            input: some_data
            enhancername: geo_enhancer
            fields: zip
    - write:
            input: some_data
            writername: csv_writer
            output_dir: /home/omnibrain/outputs
            columns: [id, latitude, longitude, zip, networktype]
            filename: example1 # the output filename

And this is the complete stack trace:

Traceback (most recent call last):
  File "/usr/local/bin/someproject", line 9, in <module>
    load_entry_point('someproject==0.0.1', 'console_scripts', 'someproject')()
  File "/usr/local/lib/python3.4/dist-packages/someproject-0.0.1-py3.4.egg/someproject/__init__.py", line 19, in main
    pipeline.Pipeline(parser.parse_args().scriptfile).start()
  File "/usr/local/lib/python3.4/dist-packages/someproject-0.0.1-py3.4.egg/someproject/pipeline/pipeline.py", line 20, in __init__
    self._raw_pipeline = self._parse_yaml(yamlscript)
  File "/usr/local/lib/python3.4/dist-packages/someproject-0.0.1-py3.4.egg/someproject/pipeline/pipeline.py", line 55, in _parse_yaml
    data = yaml.load(yamlscript)
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/__init__.py", line 72, in load
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/constructor.py", line 35, in get_single_data
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 36, in get_single_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 55, in compose_document
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 84, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 133, in compose_mapping_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 82, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 111, in compose_sequence_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 84, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 133, in compose_mapping_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 84, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 127, in compose_mapping_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/parser.py", line 98, in check_event
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/parser.py", line 428, in parse_block_mapping_key
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/scanner.py", line 116, in check_token
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/scanner.py", line 220, in fetch_more_tokens
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/scanner.py", line 580, in fetch_value
yaml.scanner.ScannerError: mapping values are not allowed here
  in "./test1.yaml", line 3, column 93

On line 3 I don't see 93 columns on text. Only about 60. So maybe it's a lime break issue. Try to check the line endings. — 0xGiddi, Sep 17 '15 at 23:47

score 6 · Answer 1 · edited Feb 26 '16 at 05:23

You are not missing any spaces after the colon, you have too many spaces in the line starting with input: /home/omnibrain/projects/company/data/data.csv. That is why you see line 3 column 93

That whole line reads something like:

      input: /home/omnibrain/projects/company/data/data.csv                           output: some_data

It also should have some funny characters messing with your display as normally you would see a string

...                           output: some_data

below the mappings not allowed here.

That kind of differences normally occur if the files look the same, but in reality are not, e.g. after copy and paste from one terminal to another. Or after pasting into a website like YAMLlint.

Generate an md5sum on both systems for the file to check if they are really the same. Use od -c on the YAML file to inspect it for strange characters.

PyYAML error: "yaml.scanner.ScannerError: mapping values are not allowed here"

1 Answers1