I've installed 4.0 pre-alpha on to a brand-new Dell and taken a local copy of 40rolling with: rsync -av --delete www.mirrorservice.org::ftp.scientificlinux.org/linux/scientific/40rolling/i386 40rolling/ I'm now unsuccessfully trying to use yum to upgrade. Since this is the first time I've used yum it's as likely that I'm doing something wrong as it is to be an SL problem. yum update yum is fine, but yum upgrade gives me a whole load of OK-looking output ending with: ---> Package mozilla.i386 37:1.7.6-1.4.1 set to be updated ---> Package tetex-fonts.i386 0:2.0.2-22.EL4.4 set to be updated --> Running transaction check --> Processing Dependency: libcom_err.so.3 for package: squid --> Finished Dependency Resolution Error: Missing Dependency: libcom_err.so.3 is needed by package squid Am I doing something wrong or is it a 4.0/yum problem? FWIW, sl.repo and sl-errata.repo are: [main] [sl-base] name=SL 4 base baseurl=file:///nfs/SL/40rolling/$basearch/SL/RPMS/ #baseurl=ftp://ftp.scientificlinux.org/linux/scientific/$releasever/$basearch/SL/RPMS/ enabled=1 [main] [sl-errata] name=SL 4 base baseurl=file:///nfs/SL/40rolling/$basearch/errata/SL/RPMS/ #baseurl=ftp://ftp.scientificlinux.org/linux/scientific/$releasever/$basearch/errata/SL/RPMS/ enabled=1 and both directories exist and are full of rpms. Thanks John