@小鱼 (Sorry I haven't figured out how to install Chinese typing method on my Ubuntu)... I have the same problem, and previous solutions don't not work for me. Below is my error message:
ERROR: Rosdep experienced an error: Expected file type is 'distribution'
Please go to the rosdepc page [1] and file a bug report with the stack trace below.
[1] : http://www.ros.org/wiki/rosdepc
发生错误了，请关注微信公众号：鱼香ROS，找小鱼反馈哦
rosdepc version: 0.21.0
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/roscdep2/main.py", line 146, in rosdep_main
exit_code = _rosdep_main(args)
File "/usr/local/lib/python3.6/dist-packages/roscdep2/main.py", line 446, in _rosdep_main
return _no_args_handler(command, parser, options, args)
File "/usr/local/lib/python3.6/dist-packages/roscdep2/main.py", line 455, in _no_args_handler
return command_handlerscommand
File "/usr/local/lib/python3.6/dist-packages/roscdep2/main.py", line 685, in command_update
ros_distro=options.ros_distro)
File "/usr/local/lib/python3.6/dist-packages/roscdep2/sources_list.py", line 516, in update_sources_list
rosdep_data = get_gbprepo_as_rosdep_data(dist_name)
File "/usr/local/lib/python3.6/dist-packages/roscdep2/gbpdistro_support.py", line 149, in get_gbprepo_as_rosdep_data
distro_file = get_release_file(gbpdistro)
File "/usr/local/lib/python3.6/dist-packages/roscdep2/rosdistrohelper.py", line 77, in get_release_file
dist_file = rosdistro.get_distribution_file(get_index(), distro)
File "/usr/local/lib/python3.6/dist-packages/rosdistro/init.py", line 120, in get_distribution_file
return create_distribution_file(dist_name, data)
File "/usr/local/lib/python3.6/dist-packages/rosdistro/distribution_file.py", line 134, in create_distribution_file
dist_file = DistributionFile(dist_name, d)
File "/usr/local/lib/python3.6/dist-packages/rosdistro/distribution_file.py", line 45, in init
assert 'type' in data, "Expected file type is '%s'" % DistributionFile._type
AssertionError: Expected file type is 'distribution'