How to fix yum error: database disk image is malformed

If you encounter “Error: database disk image is malformed” when using yum to install or update a package, as shown below:

[[email protected] ~]# yum install ruby
Loaded plugins: fastestmirror, langpacks, presto, refresh-packagekit
Loading mirror speeds from cached hostfile
 * base: mirror1.ku.ac.th
 * epel: mirror1.ku.ac.th
 * extras: mirror1.ku.ac.th
 * updates: mirror1.ku.ac.th
Error: database disk image is malformed

Fix it by running:

[[email protected] ~]# yum clean dbcache

or

[[email protected] ~]# yum clean all