In your media library, you want to enable search for binary files (PDF, Word document, and so on).
<rule source="*.File" destination="FileIndex" /> and restart the instance. Rebuild your search index to index the preexisting binary files.
<atomindex> <!-- Defines a single rule to match a source atom and define its indexing atom. Attributes: source Defines the GlobPattern to match against the qualified ID of the atom's AtomInfo. If the pattern matches, the rule applies. The first rule in the list of rules applies. destination The label of the atom taking the text extraction of the source atom. --> <rule source="*.file" destination="fileindex" /> <!-- uncomment to enable indexing of media library downloads <rule source="*.File" destination="FileIndex" /> --> <rule source="*.DownloadFile" destination="DownloadFileIndex" /> </atomindex>