有个别朋友遇到这样的问题，尤其是使用fedora的人们，升级过程中出现错误，提示下面的信息：
upgrading all packages with command yum -y update ..
there was a problem importing one of the python modules
required to run yum. the error leading to this problem was:
libxml2.so.2: cannot open shared object file: no such file or directory
please install a package which provides this module, or
verify that the module is installed correctly.
it’s possible that the above module doesn’t match the
current version of python, which is:
2.5.1 (r251:54863, oct 30 2007, 13:54:11)
[gcc 4.1.2 20070925 (red hat 4.1.2-33)]
if you cannot solve this problem yourself, please go to
the yum faq at:
http://wiki.linux.duke.edu/yumfaq
.. upgrade failed!
这样解决呢，我来告诉你，首先在网上搜索“libxml2.so.2”，我这里搜索后打开的是http://rpmfind.net/linux/rpm2html/search.php?query=libxml2.so.2
从里面下载对应的“libxml2.so.2”rpm文件，传到服务器上运行安装后就可以了正常使用了！