我在Anaconda Prompt中尝试了以下操作：
conda install -c r r-mass
以及
conda install -c conda-forge r-mass
和其他一些标签。
我收到此错误：
The following NEW packages will be INSTALLED:
r-mass: 7.3_50-r351hf348343_0
The following packages will be UPDATED:
cryptography: 2.3.1-py37h74b6da3_1000 conda-forge --> 2.4.2-py37h7a1dbc1_0
openssl: 1.0.2p-hfa6e2cd_1002 conda-forge --> 1.1.1a-he774522_0
pycurl: 7.43.0.2-py37h74b6da3_0 --> 7.43.0.2-py37h7a1dbc1_0
qt: 5.9.6-vc14h1e9a669_2 --> 5.9.7-vc14h73c81de_0
The following packages will be DOWNGRADED:
ca-certificates: 2018.11.29-ha4d7672_0 conda-forge --> 2018.10.15-ha4d7672_0 conda-forge/label/gcc7
krb5: 1.16.2-h038dc86_1000 conda-forge --> 1.16.1-hc04afaa_7
libssh2: 1.8.0-hc4dcbb0_1003 conda-forge --> 1.8.0-h7a1dbc1_4
Proceed ([y]/n)? y
Preparing transaction: done
Verifying transaction: done
Executing transaction: - WARNING conda.gateways.disk:exp_backoff_fn(49): Uncaught backoff with errno EEXIST 17
WARNING conda.gateways.disk:exp_backoff_fn(49): Uncaught backoff with errno EEXIST 17
failed
ERROR conda.core.link:_execute(507): An error occurred while uninstalling package 'conda-forge::cryptography-2.3.1-py37h74b6da3_1000'.
FileExistsError(17, 'Cannot create a file when that file already exists')
Attempting to roll back.
Rolling back transaction: done
FileExistsError(17, 'Cannot create a file when that file already exists')
FileExistsError(17, 'Cannot create a file when that file already exists')
我还尝试通过Anaconda UI安装r-mass，这没有任何错误或其他通知，但最终没有安装。