Anaconda 4.7.5 - Warning about conda-build <3.18.3 and issues with python packages

conda activate base  # or just conda deactivate
conda update conda-build

(Or simply conda update -n base -c defaults conda-build)

If this doesn't fix, try rolling back to before your update to 4.7.5, as @LeninGF suggests, then removing conda metadata, cleaning up conda, then try the update again i.e.

conda list --revisions  # find number, x, before the update
conda install --revision x
rm -rf ~/.conda
conda clean --all
conda update conda