이 yum 문제를 해결하는 방법: "reformd 파일이 없습니다."

저는 Fedora 20을 사용하고 있으며 여러 패키지를 설치하려고 합니다. 예를 들어

sudo yum install python-matplotlib

그리고 이런 답변을 받았습니다모든내가 시도한 패키지:

Loaded plugins: langpacks, refresh-packagekit
adobe-linux-i386                                         |  951 B  00:00     
epel/i386/metalink                                       |  38 kB  00:00     
Could not parse metalink https://mirrors.fedoraproject.org/metalink repo=epel-7&arch=i386 error was 
No repomd file


One of the configured repositories failed (Unknown),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Disable the repository, so yum won't use it by default. Yum will then
        just ignore the repository until you permanently enable it again or use
        --enablerepo for temporary usage:

            yum-config-manager --disable <repoid>

     4. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

File /var/cache/yum/i386/20/epel/metalink.xml does not exist

나는 이러한 제안을 자신 있게 시도해 볼 만큼 잘 이해하지 못합니다.

인터넷에서 해결방법을 검색해서 시도해봤는데..

sudo yum clean all
sudo yum update -y

...문제에 아무런 영향을 미치지 않습니다.

이...

[Harry@localhost]~% cat /etc/fedora-release
Fedora release 20 (Heisenbug)
[Harry@localhost]~% sudo yum distro-sync --releasever=20

...동일한 "재문 파일 없음" 오류가 발생합니다.

누구든지 이 문제를 해결하도록 도와주실 수 있나요?