A teacher reported a recurring error with students file upload using the assignment module. Apparently, Moodle creates a directory for the upload attempt but does not save the file, and shows a error message saying that the file was not found on the server. Strangely enough, it happens often (2/3 of the upload attemps!) but not always...
I've checked the size of the files, the names have no space or special characters. Any idea of what the problem could be?