Conda activate not working?

 gonzo  ~/a/packages  conda env list
# conda environments:
#
ppo_latest               /nohome/jaan/abhishek/anaconda3/envs/ppo_latest
root                  *  /nohome/jaan/abhishek/anaconda3

 gonzo  ~/a/packages  conda activate ppo_latest
 gonzo  ~/a/packages  which python                                                                                     (ppo_latest)
/nohome/jaan/abhishek/anaconda3/bin/python
 gonzo  ~/a/packages  conda deactivate                                                                                 (ppo_latest)
 gonzo  ~/a/packages  which python
/nohome/jaan/abhishek/anaconda3/bin/python

The environment gets activated without an error. Then we check which python it is referring to it. It is doesn't change, why?

As of conda 4.4, the command

conda activate <envname>

is the same on all platforms. The procedure to add conda to the PATH environment variable for non-Windows platforms (on Windows you should use the Anaconda Prompt), as well as the change in environment activation procedure, is detailed in the release notes for conda 4.4.0.

For conda versions older than 4.4, command is either

source activate <envname>

on Linux and macOS or

activate <envname>

on Windows. You need to remove the conda.

Functions are not exported by default to be made available in subshells. I'd recommend you do:

source ~/anaconda3/etc/profile.d/conda.sh
conda activate my_env

In the commands above, replace ~/anaconda3/ with the path to your miniconda / anaconda installation.

I just ran into a similar issue. Recently started developing on windows, so getting used to the PowerShell. Ironically when trying to use 'conda activate ' in Git-bash i got the error

$ conda activate obf

CommandNotFoundError: Your shell has not been properly configured to use 'conda activate'.
If using 'conda activate' from a batch script, change your
invocation to 'CALL conda.bat activate'.

To initialize your shell, run

    $ conda init <SHELL_NAME>

Currently supported shells are:
  - bash
  - cmd.exe
  - fish
  - tcsh
  - xonsh
  - zsh
  - powershell

See 'conda init --help' for more information and options.

IMPORTANT: You may need to close and restart your shell after running 'conda init'. 

Running the command in my PowerShell (elevated) as instructed did the trick for me.

conda init powershell 

This should be true across all terminal environments, just strange PowerShell didn't return this error itself.

To use "conda activate" via Windows CMD, not the Anaconda Prompt:
(in response to okorng's question, although using the Anaconda Prompt is the preferred option)

First, we need to add the activate.bat script to your path:
Via CMD:

set PATH=%PATH%;<your_path_to_anaconda_installation>\Scripts

Or via Control Panel, open "User Accounts" and choose "Change my environment variables".

Then calling directly from Windows CMD:

activate <environment_name>

without using the prefix "conda".

(Tested on Windows 7 Enterprise with Anaconda3-5.2.0)