Just had yum update cause a "Metadata file does not match checksum"

As usual Google had an answer but for me it didn't work...

My error was caused by danguardian web filtering blocking the download of the yum repository metadata files

Dansguardian is configured with "blockdownloads = off"

So the fix in dansguardian config files the blockdownloads = off
exceptionextensionlist = '/etc/dansguardian/lists/exceptionextensionlist'
exceptionmimetypelist = '/etc/dansguardian/lists/exceptionmimetypelist'
#
# Use the following lists to block specific kinds of file downloads.
# The two exception lists above can be used to override these.
#
bannedextensionlist = '/etc/dansguardian/lists/bannedextensionlist'
bannedmimetypelist = '/etc/dansguardian/lists/bannedmimetypelist'

Open "/etc/dansguardian/lists/exceptionextensionlist"
.gz
.bz2
.rpm