If DEVONthink does not recognize a file, make sure the file has a proper file name extension. DEVONthink needs a file name extension to determine the file type. Add the correct file name extension to your files (e.g., .txt for plain text files, .rtf for rich text files, .pdf for PDFs and .doc for Microsoft Word files) and try again.

Also, while DEVONthink supports importing many different file types, there are thousands of types and we can't guarantee trouble-free importing or usefulness with every type.

DEVONthink uses Apple's Quick Look technology to display previews of many file formats. If a document is not properly displayed, especially if it is a proprietary file format, it may be you don't have a Quick Look plugin installed for this file type or the application that created the file is not installed on your Mac (and supports Quick Look). Control-click the file and choose Show In Finder to reveal it. With the file selected in the Finder, press the spacebar to open a Quick Look window to determine if the item is viewable.

Bad PDFs: PDFs have been around so long, it would seem they'd be easily supported in DEVONthink. However, the truth is there are many bad PDFs out there. If you encounter a bad PDF, try acquiring a new copy of the file.

No Text: You will receive a "No Text" log message with PDFs having no text layer, i.e.,, scans that have not had OCR run on them. In order for their text to be searchable, you must run OCR on them.

Protected PDFs: DEVONthink cannot extract the text part of print- or edit-protected PDFs. When you import these PDFs, you get a log entry that tells you that the file contains "no text". When you select these PDFs in DEVONthink, the status bar shows Image instead of PDF+text.

One potential solution for this problem is Michele Balistreri's PDFKey. It allows you to print protected PDFs. Use PDFKey to "print" a PDF file into a new PDF that is both printable and editable, which allows DEVONthink to extract the text for searching and classifying.