When upgrading sites from an earlier version of Umbraco prior to v4.7.0 you may encounter the following exception when trying to create new media items:
The create dialog for "Media" does not match anything defined in the "~/umbraco/config/create/UI.xml". This could mean an incorrectly installed package or a corrupt UI file
There is an easy fix for this and sadly is due simply to the incorrect casing of the 'Media' nodeType defined in the UI.xml configuration file. To fix simply open the ~/umbraco/config/create/UI.xml file in your preferred text editor and locate the following line:
[code language="xml"]<nodeType alias="media">[/code]
Simply change the word media to have an uppercase 'm' and save the file and your problems will go away!
[code language="xml"]<nodeType alias="Media">[/code]
Update: As per the comment by Petr Snobelt, for future compatibility it is possibly best to change the case in the database rather than the UI.xml file