"Unsupported Pickle Protocol: 4" when calling rospack depends returning

[BenGHolmes]

Slowly working my way through the ROS tutorials. I followed the install instructions for Ubuntu 16.04 here (http://wiki.ros.org/kinetic/Installation/Ubuntu) and all seemed to go ok. After creating the workspace and a beginner_tutorials package, I tried following the tutorial by running rospack depends1 beginner_tutorials but this failed giving me the following error:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/rosdep2/rospack.py", line 59, in init_rospack_interface
    lookup = _get_default_RosdepLookup(Options())
  File "/usr/lib/python2.7/dist-packages/rosdep2/main.py", line 130, in _get_default_RosdepLookup
    verbose=options.verbose)
  File "/usr/lib/python2.7/dist-packages/rosdep2/sources_list.py", line 633, in create_default
    sources = load_cached_sources_list(sources_cache_dir=sources_cache_dir, verbose=verbose)
  File "/usr/lib/python2.7/dist-packages/rosdep2/sources_list.py", line 533, in load_cached_sources_list
    return parse_sources_data(cache_data, origin=cache_index, model=model)
  File "/usr/lib/python2.7/dist-packages/rosdep2/sources_list.py", line 388, in parse_sources_data
    raise InvalidData('line:\n\t%s\n%s' % (line, e), origin=origin)
rosdep2.core.InvalidData: line:
	yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx
unsupported pickle protocol: 4
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/rosdep2/rospack.py", line 59, in init_rospack_interface
    lookup = _get_default_RosdepLookup(Options())
  File "/usr/lib/python2.7/dist-packages/rosdep2/main.py", line 130, in _get_default_RosdepLookup
    verbose=options.verbose)
  File "/usr/lib/python2.7/dist-packages/rosdep2/sources_list.py", line 633, in create_default
    sources = load_cached_sources_list(sources_cache_dir=sources_cache_dir, verbose=verbose)
  File "/usr/lib/python2.7/dist-packages/rosdep2/sources_list.py", line 533, in load_cached_sources_list
    return parse_sources_data(cache_data, origin=cache_index, model=model)
  File "/usr/lib/python2.7/dist-packages/rosdep2/sources_list.py", line 388, in parse_sources_data
    raise InvalidData('line:\n\t%s\n%s' % (line, e), origin=origin)
rosdep2.core.InvalidData: line:
	yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx
unsupported pickle protocol: 4
[rospack] Error: could not call python function 'rosdep2.rospack.init_rospack_interface'

Googling it hasn't turned up anything useful. Apparently it could be some kind of python2 vs python3 issue but I'm not sure. Any thoughts?

[dirk-thomas]

The highest pickle format in Python 2(.7) is 2 where in Python 3(.6) it is 4. See duplicate ticket ros-infrastructure/rosdep#379.