CondaHTTPError HTTP 404 NOT FOUND for url httpsmirrors

CondaHTTPError: HTTP 404 NOT FOUND for url https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main/noarch/repodata.json

环境：

• Ubuntu / 14.04.1
• conda 4.5.12

错误：

今天用conda创建虚拟环境报这个错误：

Solving environment: failed

CondaHTTPError: HTTP 404 NOT FOUND for url <https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main/noarch/repodata.json>
Elapsed: 00:00.148028

The remote server could not find the noarch directory for the
requested channel with url: https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main

As of conda 4.3, a valid channel must contain a `noarch/repodata.json` and
associated `noarch/repodata.json.bz2` file, even if `noarch/repodata.json` is
empty. please request that the channel administrator create
`noarch/repodata.json` and associated `noarch/repodata.json.bz2` files.
$ mkdir noarch
$ echo '{}' > noarch/repodata.json
$ bzip2 -k noarch/repodata.json

You will need to adjust your conda configuration to proceed.
Use `conda config --show channels` to view your configuration's current state.
Further configuration help can be found at <https://conda.io/docs/config.html>.

解决：

conda config --remove-key channels # 恢复默认下载源

原因：

之前将conda的下载源换成了清华镜像，但是由于清华大学停止了Anaconda镜像服务，所以镜像失效了，需要更换下载源。