xyj@minecraft:~$ conda install numpy
Solving environment: failed
InvalidVersionSpecError: Invalid version spec: =2.7
最近使用conda遇到了报错，发现conda的issues有人提出了这个问题：https://github.com/conda/conda/issues/10618
今天终于有了回复了说：I personally solved it by deleting the line conda-forge inside the .condarc config file and by not using conda-forge while installing packages/new envs. Hope it helps someone.
按照这个方法，编辑用户目录下的.condarc ( 例如windows就是：C:Usersadmin.condarc ，Linux一般是~/.condarc
删除带有：conda-forge 的那一行，成功解决！