I'm getting "yum error no such table packages", how do I fix corrupted db?

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http://serverfault.com – I'm trying to use following guide: Scientific Linux - How To Upgrade To The Latest S.L. 6.x Release to update my Scientific Linux release 6.3 to Scientific Linux release 6.4. # yum update --releasever=6.4 Loaded plugins: refresh-packagekit, security Error: no such table: packages # cat /etc/redhat-release Scientific Linux release 6.3 (Carbon) # uname -a Linux XXXXX.XXXXX.XXX 2.6.32-358.18.1.el6.x86_64 #1 SMP Tue Aug 27 14:23:09 CDT 2013 x86_64 x86_64 x86_64 GNU/Linux # rpm -q yum yum-3.2.29-30.el6.noarch # I went through steps outlined in Docs/RpmRecovery - rpm - Trac, still same result (HowTos)