The Anaconda environment was corrupted when I thought the Jupyter Notebook wouldn't start

2019/4/122019/11/18

When I put a new package with pip, it seems that the conda environment is broken.In this article, we will record the origin, the cause investigation / confirmation method, and the solution.

The environment when this accident occurred is as follows. OS is windows 10.

conda version: 4.6.8 conda-build version: not installed python version: 3.7.2.final.0 OS: Windows 10 64 bit

The beginning of the matter

One day, when I started Jupyter Notebook as usual, a window popped out and disappeared in an instant.Even if you try again or restart your computer, it doesn't change at all ...

I put it in a new package with the pip I put in just before, so I thought that I should update everything for the time being, from the Anaconda prompt
・ Conda itself update ( conda update -n base conda)
-Update all installed packages (conda update --all)
I tried.

Then the following display is ...

Solving environment: / WARNING conda.common.logic: get_sat_solver_cls (278): Could not run SAT solver through interface'pycosat'. Failed CondaDependencyError: Cannot run solver. No functioning SAT implementations available.

Apparently the "SAT solver" isn't working well.

On the official pageArticle about how conda worksIt seems that conda is using the SAT solver to "collect metadata for all packages in the environment and verify that their dependencies are properly met".

The fact that the packages in the environment cannot be grasped means that something has happened to the environment.

Confirmation method

In conclusion, it was due to a collision between conda and pip.For the cause, I referred to the following site very much.

conda and pip: Danger of mixing

“Using pip under Anaconda will unexpectedly destroy the environment and in the worst case will require you to reinstall Anaconda itself.”
"If you want to see if there is a pip and conda conflict in your already built conda environment,conda listTo execute. "

Your own environmentconda listIf you check with, there are certainly some overlaps (highlighted on a white background in the image).

In addition, "pypi" is displayed on the far rightpip installBy, unmarkedconda installIt is by.

This may have clashed with what was installed by pip, making the SAT solver unable to run, resulting in the conda environment itself getting stuck.

Reinstall Anaconda

You cannot uninstall using Anaconda-Clean because the Anaconda prompt does not work.

Remove it from [Uninstall a program] in [Control Panel] and reinstall it.Details are also summarized below.

Difference between conda install and pip installI also investigated about, so I would appreciate it if you could refer to it.