import failed error - Workaround
If you receive an "import failed. Our system was unable to process this document" error after importing a .jpg or .png then redacting it, I have a workaround.
Convert or save the .jpg or .png (may work with other image types also..I've only tested it with these two) to .pdf outside documentcloud. Add .PDF document to DocumentCloud. Do the redacting. click 'save'. the document should import without any issues.