Introduction

If you need Python 3.6 with Conda, the safest approach is usually to create a separate environment instead of changing your base environment in place. Python 3.6 is a legacy version now, so environment isolation matters even more than usual.

Prefer a New Environment

Create a dedicated environment for the old Python version:

conda create -n py36 python=3.6
conda activate py36
python --version

This is better than downgrading an existing environment because it avoids breaking packages that expect a newer interpreter.

If the project needs extra packages, install them after activation:

conda install numpy pandas

Upgrade or Downgrade an Existing Environment

If you really must change the Python version inside an existing Conda environment, activate it first:

conda activate myenv
conda install python=3.6

Conda will try to solve dependencies around that request. Sometimes it succeeds, and sometimes it forces package changes that are larger than you expected.

That is exactly why a fresh environment is usually safer.

Verify What You Actually Got

After the install, confirm both the interpreter and the active environment:

python --version
conda info --envs

It is easy to think you upgraded one environment while your shell is still pointing at another one.

If you want to confirm that your configured channels can still resolve that interpreter version, check availability directly:

conda search python=3.6

That is a quick sanity check before you ask Conda to rewrite the environment. It can save you time before a long solver run. It is a cheap check to make. Do it first.

Be Ready for Dependency Solving

Requesting Python 3.6 can force Conda to downgrade or remove packages that require a newer interpreter. If the solver reports conflicts, that is a sign that the environment may have drifted too far from what Python 3.6 can support.

That is another reason a fresh environment is usually better than modifying an existing one.

Why This Is a Legacy-Only Move

Python 3.6 is end-of-life, so most modern projects should not target it unless they are maintaining an older dependency stack. New work should normally use a currently supported Python version.

In other words, creating a Python 3.6 Conda environment is usually a compatibility task, not a general upgrade strategy.

Export the Environment if It Matters

If you are creating Python 3.6 for a legacy project that other people need to reproduce, export the environment once it works:

conda env export > environment.yml

That gives the team a record of the exact package set that worked with the older interpreter.

You can then recreate it elsewhere with conda env create -f environment.yml, which is often more reliable than asking everyone to remember the exact install steps.

Common Pitfalls

• Downgrading base is risky and can break your general Conda setup.
• Changing Python inside an existing environment may force unexpected dependency removals or replacements.
• Verifying with python --version matters because shell activation mistakes are common.
• Python 3.6 is a legacy compatibility target now, so use it only when a project truly requires it.

Summary

• The safest Conda path to Python 3.6 is conda create -n py36 python=3.6.
• Activate the environment and verify the version immediately afterward.
• Avoid downgrading base unless you have a very specific reason.
• Treat Python 3.6 as a legacy environment requirement, not as a modern default.