You may get an error are Yum attempting to Update or when you installing Packages, 404 Error Returned. 



#  yum update



Loaded plugins: fastestmirror

Loading mirror speeds from cached hostfile

 * base: mirror.chpc.utah.edu

 * epel: mirror.chpc.utah.edu

 * extras: mirrors.usc.edu

 * updates: mirrors.cat.pdx.edu

http://mirror.chpc.utah.edu/pub/centos/6.6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"

Trying other mirror.

http://linux.mirrors.es.net/centos/6.6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"


Verify that channel is not listed and then add the same channel again by :-



# yum repolist



# yum clean all


If the above commands could not solve an error, let us run a few more commands that will make sure you have a clean and up to date version of yum:



# yum check 



# yum upgrade