I've finally managed to update one of my boxes to 5.7. I did it in a very roundabout way, which however confirms that at least in my boxes there's something wrong in the way yum creates the sqlite databases. I've basically followed the guide at http://wiki.centos.org/HowTos/CreateLocalMirror to create my own mirror of the 5.7 'os' and 'updates' directories, created the yum repository with 'createrepo -d' to pre-create the sqlite database and made this mirror accessible to the other boxes via HTTP. I then created a /etc/yum.repos.d/Local.repo file which specifies my private mirror for the [base] and [updates] repositories, commented out everything in the /etc/yum.repos.d/CentOS-Base.repo and ran yum clean all yum update Everything updated flawlessly and the box restarted normally with the newer kernel. Now, this doesn't solve the original yum problem, but at least confirms that the creation of a corrupted sqlite database was indeed the real issue. Many thanks to all the people on the list who have suggestions and advice, particularly to Alain Péan who pointed me in the right direction. Have a nice weekend Sebastiano Pilla