Conda install package ModuleNotFoundError: No module named 'conda'

Question

I installed Conda using the scripts from bootstrap-conda.sh and install-conda-env.sh

Conda was installed successfully. When I install the first package,

e.g., conda install --yes lxml=4.3.0

it worked fine. The log can be found here. But when I tried to install the second package,

e.g., 'conda install --yes numpy=1.15.4'

it throws this error:

Traceback (most recent call last):
  File "/opt/conda/default/bin/conda", line 12, in <module>
    from conda.cli import main
ModuleNotFoundError: No module named 'conda'

Tried every possible solution I could find, it did not help.

Before package installation, when I type python, it takes me to Python 3.6.7

Python 3.6.7 | packaged by conda-forge | (default, Feb 28 2019, 09:07:38)
[GCC 7.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.

python default import path:

/opt/conda/default/lib/python36.zip
/opt/conda/default/lib/python3.6
/opt/conda/default/lib/python3.6/lib-dynload
/opt/conda/default/lib/python3.6/site-packages
/usr/lib/spark/python

After package installation, when I type python, it takes me to Python 3.7.3

Python 3.7.3 (default, Mar 27 2019, 22:11:17) [GCC 7.3.0] :: Anaconda, Inc. on linux Type "help", "copyright", "credits" or "license" for more information.

python default import path:

/opt/conda/default/lib/python37.zip
/opt/conda/default/lib/python3.7
/opt/conda/default/lib/python3.7/lib-dynload
/opt/conda/default/lib/python3.7/site-packages

I re-installed Conda. The same problem still persists.

Conda Version:

conda --version

conda 4.6.14

When I install the first package, the following log caught my attention. It upgraded python from 3.6 to 3.7. I am not sure if this is what causes the problem.

The following packages will be UPDATED:

  certifi              conda-forge::certifi-2019.3.9-py36_0 --> pkgs/main::certifi-2019.6.16-py37_0
  libedit                           3.1.20170329-h6b74fdf_2 --> 3.1.20181209-hc058e9b_0
  ncurses                                    6.1-hf484d3e_0 --> 6.1-he6710b0_1
  openssl            conda-forge::openssl-1.1.1b-h14c3975_1 --> pkgs/main::openssl-1.1.1c-h7b6447c_1
  pip                                         10.0.1-py36_0 --> 19.1.1-py37_0
  python             conda-forge::python-3.6.7-h381d211_10~ --> pkgs/main::python-3.7.3-h0371630_0
  readline                                   7.0-ha6073c6_4 --> 7.0-h7b6447c_5
  setuptools                                  39.2.0-py36_0 --> 41.0.1-py37_0
  wheel                                       0.31.1-py36_0 --> 0.33.4-py37_0
  zlib                                    1.2.11-ha838bed_2 --> 1.2.11-h7b6447c_3

Answer 1

You should create a dedicated environment for your lxml and numpy. That will keep the prerequisites for conda and for your code separate, which brings benefits in the long run.

About two weeks ago, conda started to aggressively update Python, and probably other packages too. You can try to prevent that by passing python=3.6 with every install command, or by pinning the Python version. This answer might help: https://stackoverflow.com/a/48733093/5629418

Answer 2

Like you assumed, upgrading Python version is what making you an issue. If you try to downgrade it, the same thing can happen in some cases. This means that Conda will be broken if you do not explicitly say to keep existing Python version (not always, but in some cases). In your case you should do following:

conda install --yes lxml=4.3.0 python=3.6.7
conda install --yes numpy=1.15.4 python=3.6.7

Not sure is this an Conda bug and not sure why it started to happening in the last few weeks, but probably because of some change in its update strategy (maybe really Conda started to aggressively update Python, like @Roland Weber mentioned).