How to downgrade conda version?

Question

I need to downgrade my conda version from 4.3 to 4.2 on my CentOS 6.7 machine. What is the command required to do that?

Answer 1

I wouldn't recommend downgrading conda except when the newly installed (upgraded) version has a critical bug.

But since you asked: You can specify a version by appending ={version} to the packages, this works even for the conda package:

$ conda install conda=4.2

If you want a specific 4.2 version you can also use (for example):

$ conda install conda=4.2.15

Note that downgrading conda can be very risky. After the downgrade your conda could fail completely or work incorrectly. Conda uses a lot of metadata that evolve over time ... so if the downgraded conda version cannot make sense of these - or even worse corrupt them - you'll have a painful experience in how to recover your conda environemnt. Downgrade conda at your own risk (and in my opinion only if really, really necessary)!

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In case you already downgraded conda and it's throwing exceptions (for example CondaUpgradeError) at you, then maybe this "section" in an troubleshooting guide in the conda repository may be useful:

Conda upgrade error

Cause

Downgrading conda from 4.6.1 to 4.5.x and then trying to conda install conda or conda upgrade conda will produce a solving and upgrade error similar to the following:

Solving environment: failed
CondaUpgradeError: This environment has previously been operated on by a
conda version that's newer than the conda currently being used. A newer
version of conda is required.
target environment location: /opt/conda
current conda version: 4.5.9
minimum conda version: 4.6

Solution

Change the .condarc file. Set the parameter by editing the .condarc file directly: allow_conda_downgrades: true in conda version 4.5.12. This will then let you upgrade. If you have something older than 4.5.12, install conda 4.6.1 again from the package cache.

EXAMPLE: If my conda info says package cache : /opt/conda/pkgs and my Python version is 3.7, then on the command line, type conda install /opt/conda/pkgs/conda-4.6.1-py37_0.tar.bz2 to resolve the issue.