i have qiime2-2020.6 version but i want to update 2020.8 in my macbook, when i am trying to upadte it it deny and showng this text.
It looks like some of the packages downloaded are now corrupt. You can attempt to clean up the package cache by running:
conda clean --all
You might also need to remove the 2020.8 conda environment, first:
conda env remove -n 2020.8
Keep us posted!