When we migrated documents from file share to SharePoint 2013 document libraries, users reported that some files are not searchable. When we looked at the search craw logs, we identified many “The object was not found.” Errors. After looking closely at these documents, we have noticed that they are all under folder named “AUX”. In another word, any document under folder named “AUX” will fail in the crawl and will not be searchable.
AUX is one of the folders that is forbidden on window and there are many other folders similar to it. We believe SharePoint may not be able to craw any documents under all of such window forbidden folders. However, we are not able to find any information from SharePoint side.
If you find documents are not searchable, you might need to verify if the documents are under such folder that is forbidden on window.