File names can contain various punctuation marks. However, some punctuation marks may have technically undesirable effects. The following punctuation marks are allowed in a file name:
lower case
capitals
digits
dot
spaces
minus sign -
underscore _
open parenthesis (
close parenthesis )
If other punctuation marks are used, the Article importer will give an error message.
Solution:
Find the file names with invalid characters and replace the invalid characters with valid ones.