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elopio
Asked: 2016-12-09 22:06:17 +0800 CST

Why does snapcraft fail with: module 'magic' has no attribute 'open'

  • 772

When trying to snap a project, we got back this error from snapcraft:

Traceback (most recent call last):
  File "/usr/bin/snapcraft", line 31, in <module>
    snapcraft.main.main()
  File "/usr/lib/python3/dist-packages/snapcraft/main.py", line 226, in main
    return run(args, project_options)
  File "/usr/lib/python3/dist-packages/snapcraft/main.py", line 282, in run
    lifecycle.snap(project_options, args['<directory>'], args['--output'])
  File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle.py", line 289, in snap
    snap = execute('prime', project_options)
  File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle.py", line 103, in execute
    _Executor(config, project_options).run(step, part_names)
  File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle.py", line 161, in run
    self._run_step(step, part, part_names)
  File "/usr/lib/python3/dist-packages/snapcraft/internal/lifecycle.py", line 197, in _run_step
    getattr(part, step)()
  File "/usr/lib/python3/dist-packages/snapcraft/internal/pluginhandler.py", line 383, in prime
    dependencies = _find_dependencies(self.snapdir, snap_files)
  File "/usr/lib/python3/dist-packages/snapcraft/internal/pluginhandler.py", line 723, in _find_dependencies
    ms = magic.open(magic.NONE)
AttributeError: module 'magic' has no attribute 'open'

What does it mean, and how can it be solved?

snap

2 Answers

  1. Best Answer

    There are two python modules named magic, with different APIs.

    The one that snapcraft requires is packaged as a deb named python3-magic. This one corresponds to the module file-magic in pypi: https://pypi.python.org/pypi/file-magic

    The other one is just called magic in pypi: https://pypi.python.org/pypi/magic

    So if you do:

    sudo pip install magic

    You will get the wrong one, and it will be installed to a path that takes precedence over the python3-magic deb installed with apt. That's what causes the error.

    To check if you have the other magic module installed from pip:

    pip3 list | grep magic

    And to remove it and fix snapcraft:

    pip3 uninstall magic
    • 2

  2. as of time of writing the solution is:

    pip3 uninstall python-magic
pip3 install file-magic
    • 0