What does it mean?

The yum message “Warning: RPMDB altered outside of yum.” or, as the yum message said for a few months, “Warning: RPMDB has been altered since the last yum transaction.” means some application has altered the rpm database (installed or removed a package) without going through the Yum APIs. This is almost always due to someone using rpm directly (Ie. rpm -ivh blah.rpm), but another possibility is an application built on top of the rpm APIs (Ie. smart, apt, zypp). While it’s possible that someone has hacked your machine and altered the rpmdb maliciously, it would have to be done poorly to trigger this warning.

Why has yum started to emit this warning?

There are three main sets of reasoning behind bringing this to the users attention.

New yum features require yum being “the” packaging API

There are now a few features in yum, requested by users of the package management system, that require yum is aware of all package actions on the system. Here a few of the current ones:

• The most obvious example is “yum history”, which records when packages were installed, when and by whom. If yum is not involved in installing/updating/removing/etc. some packages then a lot of the benefits of “yum history” are gone. For instance there is no useful audit trail anymore, you can’t use “yum history list blah” and know you have all the instances where something happened to “blah”.
• Yum now has it’s own database, for package information it wants to record but has no corresponding entry in the rpmdb, the obvious example is “the id of the repository that this package was installed from” but there are quite a few pieces of info. now.
• Following on from the previous point, rpmdb versions are a significant feature for managing many machines by yum. They require information from the yumdb, so installing something via. yum on one machine but via. rpm on another would give the machines different “rpmdb versions”.

This is not a complete list, and as more package management features are implemented they are much more likely to be implemented at the yum layer than at the rpm layer. Not because rpm is bad, but for the same reasons that the above features were implemented in yum, it’s much easier and faster to implement them there.

Solution :

# yum clean all