anacoda更新库时候出现失败HTTP 404 NOT FOUND for url 解决方法

win10+anacoda3
在更新所有库时候cnoda update --all时候出现以下代码

Solving environment: failed

CondaHTTPError: HTTP 404 NOT FOUND for url <https://conda.anaconda.org/'https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/'/noarch/repodata.json>
Elapsed: 00:00.609577
CF-RAY: 471413c728102126-LAX

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

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>.

是因为这个问题的出现是由于你conda安装好了之后，默认的镜像是官方的，由于官方的镜像在*，访问太慢或者不能访问，所以为了能够加快访问的速度，选择清华的镜像。
首先在prompt中输入以下：

conda config --add channels https://mirrors.ustc.edu.cn/anaconda/pkgs/free/ 
conda config --add channels https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge/
conda config --add channels https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/
conda config --set show_channel_urls yes

然后在c盘中用户文件中搜索.condarc这个文件，如果没有就是隐藏了，我们可以通过ctrl+h来让隐藏文件显示出来。
接着用记事本打开，删掉-defaults和其他乱七八糟的东西，只剩下这种形式：

ssl_verify: true
channels:
  - https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/
  - https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge/
  - https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/msys2/
  - https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/
 
show_channel_urls: true

接着更新就好了！