Dear all, my yum was working fine. I was just trying to remove cache from yum through yum cleanall, after that i tried to do yum update, but it failed to do update and giving fallowing error bash-4.1# yum update Loaded plugins: fastestmirror, refresh-packagekit Loading mirror speeds from cached hostfile Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=6&arch=i386&repo=os error was 14: PYCURL ERROR 22 - "The requested URL returned error: 407" Error: Cannot find a valid baseurl for repo: base i later checked the var/cache/yum and var/lib/yum.....all the "base", "extras", "updates", "centosplus", "rpmforge" folders are empty......i dont know what happened. can any one please solve this error and help me to set yum working again. Regards -- Arun Kumar Somavarapu Project-JRF Dr. Prasanna's lab TMC, ACTREC Navi Mumbai-410210