In a recent thread on Moodle.org forums, one of the fellow moodler posted that he was trying to upload the pdf file and it was showing the error “PDF Document filetype cannot be accepted”including zip files. He was able to upload only images.
After seeing the above screenshot shared by him, other moodle community member replied that since he was trying to upload the PDF file type in the course summary section, which is not set by default to accept PDF files, so he has to change the file type settings and add PDF file type.
To do so the Administrator can add PDF file type in the field “Course summary files extensions” in Administration > Site administration > Appearance > Courses.
Reference: https://moodle.org/mod/forum/discuss.php?d=309441#p1241130
