PackageNotInstalledError: Package is not installed in prefix

Usually this error, "PackageNotInstalledError: Package is not installed in prefix." is because your custom environment doesn't have the conda infrastructure. Instead, it is in your base only. To update the base environment:

conda update --name base conda

To see what version you have installed:

conda list --name base conda

example output of list;

# packages in environment at /Users/me/miniconda2:
#
# Name                    Version                   Build  Channel
conda                     4.6.14                   py27_0  
conda-env                 2.6.0                h36134e3_0  

to solve the problem after message "PackageNotInstalledError: Package is not installed in prefix" package name: anaconda:

    conda update --all
    ...
    Proceed ([y]/n)? y

regards !

I got this error when I tried to update while my conda environment was activated. The solution was to first deactivate:

conda deactivate

before trying to update:

conda update conda

conda update anaconda

I was getting the following error when trying to update boto3 in my conda environment:

PackageNotInstalledError: Package is not installed in prefix. prefix: /usr/local/anaconda3/envs/myfoldername

package name: boto3

This was after having already just done: conda install anaconda, conda update -n root conda and conda update --all

However, I did finally succeed in updating boto3, by specifying the version number as follows:

conda install boto3=1.12

I met the same problem in my window1 10. pls change the env to base, because the package "conda" only can be updated in base. regards!