Corrupted DatabaseSometimes the RPM database becomes corrupted and then it and the Yellowdog Update Manager (yum) won't work.
- Remove old RPM db: rm -f /var/lib/rpm/__db*
- Rebuild RPM db: rpm -vv --rebuilddb
- Try to update: yum update -y
TimeoutsSometimes all the mirrors time out, all the time when you have a super slow company network and then yum won't work at all.
Add timeout=60 (or more) to /etc/yum.conf and try again.
Lock FileSometimes yum gets hung up if you have a really rotten internet link and then you have to kill it. This may result in yum refusing to run the next time.
# pkill yum
(or killall yum)
Delete the PID file:
# rm /var/run/yum.pid