File upload fails for unknown media types

File upload fails for unknown media types.

This happens regardless of application, here DMX Webclient and Linqa:

The server log clarifies the error originates not in the actual upload but in the DMX PDF Search plugin:

Caused by: java.lang.RuntimeException: An error occurred in the PostCreateTopic listener of plugin "DMX PDF Search"
	at systems.dmx.core.impl.EventManager.dispatchEvent(EventManager.java:96)
	at systems.dmx.core.impl.EventManager.fireEvent(EventManager.java:59)
	at systems.dmx.core.impl.ValueIntegrator.integrate(ValueIntegrator.java:115)
	... 62 more
Caused by: java.lang.RuntimeException: Comp Def URI "dmx.files.media_type" not found in [dmx.files.file_name, dmx.files.path, dmx.files.size]
	at systems.dmx.core.impl.ChildTopicsModelImpl.getTopic(ChildTopicsModelImpl.java:62)
	at systems.dmx.core.impl.ChildTopicsImpl._getTopic(ChildTopicsImpl.java:234)
	at systems.dmx.core.impl.ChildTopicsImpl.getTopic(ChildTopicsImpl.java:59)
	at systems.dmx.pdfsearch.PDFSearchPlugin.postCreateTopic(PDFSearchPlugin.java:42)
	at systems.dmx.core.impl.CoreEvent$10.dispatch(CoreEvent.java:125)
	at systems.dmx.core.impl.EventManager.dispatchEvent(EventManager.java:83)
	... 64 more

The error does not occur if the PDF Search plugin is not installed.

@jpn FYI