[Solved] Command '/usr/local/bin/pip list --outdated --format json' returned non-zero exit status 1

[matt]

hippo@hippo-camp:~$ python3 -m pipupgrade --verbose --latest --yes
/usr/lib/python3.8/runpy.py:127: RuntimeWarning: 'pipupgrade.__main__' found in sys.modules after import of package 'pipupgrade', but prior to execution of 'pipupgrade.__main__'; this may result in unpredictable behaviour
  warn(RuntimeWarning(msg))
2021-11-23 11:21:57,858 | INFO | Environment: {'version': '0.2.0', 'python_version': '3.8.10', 'os': 'Linux-5.4.0-90-lowlatency-x86_64-with-glibc2.29', 'config': {'path': {'BASE': '/home/hippo/.local/lib/python3.8/site-packages/bpyutils', 'DATA': '/home/hippo/.local/lib/python3.8/site-packages/bpyutils/data', 'CACHE': '/home/hippo/.config/bpyutils', 'JOBS': '/home/hippo/.local/lib/python3.8/site-packages/bpyutils/jobs'}}, 'settings': {'settings': {'version': '0.2.0', 'cache_timeout': '86400', 'jobs': '4'}}}
2021-11-23 11:21:57,858 | INFO | Arguments Passed: {'args': (), 'kwargs': {'ARGUMENTS': <class 'inspect._empty'>, 'packages': [], 'resolve': False, 'ignore': None, 'pip_path': None, 'yes': True, 'clean': 0, 'check': 0, 'upgrade_type': ['minor', 'patch'], 'latest': True, 'format': 'table', 'all': 0, 'pip': 0, 'self': False, 'requirements': None, 'pipfile': None, 'interactive': 0, 'project': None, 'git_username': None, 'git_email': None, 'pull_request': False, 'github_access_token': None, 'github_reponame': None, 'github_username': None, 'target_branch': 'master', 'jobs': 4, 'user': 0, 'no_included_requirements': 0, 'no_cache': 0, 'output': None, 'ignore_error': 0, 'force': 0, 'doctor': False, 'no_color': 0, 'verbose': True}, 'a': <pipupgrade.commands.to_params.<locals>.O object at 0x7f5506f6d6d0>}
Checking...
2021-11-23 11:21:57,861 | INFO | `pip` executables found: ['/usr/local/bin/pip', '/usr/bin/pip3', '/usr/local/bin/pip2']
2021-11-23 11:21:57,861 | INFO | Using 4 jobs...
2021-11-23 11:21:57,869 | INFO | Fetching installed packages for /usr/local/bin/pip...
2021-11-23 11:21:57,869 | INFO | Fetching installed packages for /usr/bin/pip3...
2021-11-23 11:21:57,869 | INFO | Fetching installed packages for /usr/local/bin/pip2...
2021-11-23 11:21:57,870 | INFO | Executing command: /usr/local/bin/pip list --outdated --format json
2021-11-23 11:21:57,870 | INFO | Executing command: /usr/bin/pip3 list --outdated --format json
2021-11-23 11:21:57,870 | INFO | Executing command: /usr/local/bin/pip2 list --outdated --format json

concurrent.futures.process._RemoteTraceback: 
"""
Traceback (most recent call last):
  File "/usr/lib/python3.8/concurrent/futures/process.py", line 239, in _process_worker
    r = call_item.fn(*call_item.args, **call_item.kwargs)
  File "/usr/lib/python3.8/concurrent/futures/process.py", line 198, in _process_chunk
    return [fn(*args) for args in chunk]
  File "/usr/lib/python3.8/concurrent/futures/process.py", line 198, in <listcomp>
    return [fn(*args) for args in chunk]
  File "/home/hippo/.local/lib/python3.8/site-packages/pipupgrade/commands/helper.py", line 319, in get_registry_from_pip
    _, output, _ = _pip.call("list", user = user, outdated = outdated, \
  File "/home/hippo/.local/lib/python3.8/site-packages/pipupgrade/_pip.py", line 76, in call
    output = popen(*params, output = output, raise_err = raise_err)
  File "/home/hippo/.local/lib/python3.8/site-packages/bpyutils/util/system.py", line 92, in popen
    raise PopenError(code, command)
bpyutils.exception.PopenError: Command '/usr/local/bin/pip list --outdated --format json' returned non-zero exit status 1.
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/hippo/.local/lib/python3.8/site-packages/pipupgrade/commands/__init__.py", line 79, in command
    return _command(**ARGUMENTS)
  File "/home/hippo/.local/lib/python3.8/site-packages/pipupgrade/commands/__init__.py", line 240, in _command
    for registry in pool.imap_unordered(
  File "/usr/lib/python3.8/concurrent/futures/process.py", line 484, in _chain_from_iterable_of_lists
    for element in iterable:
  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 619, in result_iterator
    yield fs.pop().result()
  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 444, in result
    return self.__get_result()
  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 389, in __get_result
    raise self._exception
bpyutils.exception.PopenError: Command '/usr/local/bin/pip list --outdated --format json' returned non-zero exit status 1.

An error occured while performing the above command. This could be an issue with
"pipupgrade". Kindly post an issue at https://github.com/achillesrasquinha/pipupgrade/issues                     

[matt]

This seems to fix something wrong in pip:
For pip2.7, you can at first
curl https://bootstrap.pypa.io/pip/2.7/get-pip.py -o get-pip.py
then
python2.7 get-pip.py --force-reinstall
to reinstall pip.

When you run pipupgrade there is no more error afterwards.