yum makecache 时出错

在Linux上面配置阿里云软件源时，运行yum makecache 后出现如下错误，
base | 3.7 kB 00:00
http://mirrors.aliyun.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno -1] Error importing repomd.xml for base: Damaged repomd.xml file
尝试其他镜像。
base | 3.7 kB 00:00
http://mirrors.aliyuncs.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno -1] Error importing repomd.xml for base: Damaged repomd.xml file
尝试其他镜像。
错误：Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again

查了好多资料，都没解决，特来请教。