There are 3 things that usually cause this problem:
1- The file size is very large (over 200k words) and your browser times out. Easy fix for this is to break your file into sections.
2- Incompatible file type. We support upload of MS Word .docx and rich text .rtf files. You may need to convert your file to one of these formats first.
3 – Something in the file is not agreeing with our system. Usually a snippet of hidden formatting code. The fix may be as simple as copying just your text into a new document and resaving your file. Try to leave out any extraneous photographs, images, emojis…. and fanciful formatting.