Another app is currently holding the yum lock; waiting for it to exit

Question

Why am I presented with a message similar to the following when running an upcp?

[/usr/local/cpanel/scripts/rpmup] Another app is currently holding the yum lock; waiting for it to exit

Answer

This can sometimes occur whenever a package is being updated or is stalled.

You can run the following to help you determine why a package is holding a yum lock:

ps auxf | grep yum