Traceback (most recent call last):


 "/opt/eff.org/certbot/venv/bin/letsencrypt", line 7, in <module>

from certbot.main import main


 "/opt/eff.org/certbot/venv/local/lib/python2.7/site-packages/certbot/main.py", line 4, in <module>

import logging.handlers


 "/usr/lib/python2.7/logging/__init__.py", line 26, in <module>

import sys, os, time, cStringIO, traceback, warnings, weakref, collections


 "/usr/lib/python2.7/weakref.py", line 14, in <module>

from _weakref import (
ImportError: cannot import name _remove_dead_weakref

Traceback (most recent call last):


 "train_memory.py", line 14, in <module>

import horovod.mxnet as hvd


 "/home/liuyang/anaconda3/envs/mxnet_partial/lib/python3.6/site-packages/horovod/mxnet/__init__.py", line 23, in <module>

__file__, 'mpi_lib')


 "/home/liuyang/anaconda3/envs/mxnet_partial/lib/python3.6/site-packages/horovod/common/util.py", line 56, in check_extension

'Horovod with %s=1 to debug the build error.' % (ext_name, ext_env_var))
ImportError: Extension horovod.mxnet has not been built.
If this is not expected, reinstall Horovod with HOROVOD_WITH_MXNET=1 to debug the build error.
