The most common reason a file will not upload is special characters in the file name. To upload your document, rename the file without special characters. Special characters include symbols such as !, #, $, %, and other similar symbols.
When the file has been uploaded, the special characters can be added in the Display Name field as needed.
For a full listing of special characters, visit the Microsoft Style Guide.
Note:
These special characters apply to both Macs and PCS.