Getting some malformed data to test with Create a new course, and enrol a few users in it. Create a new assignment activity with submission types set to online text . As two students, complete the assignment. As a teacher or admin user, grade the students. Go to the course's grader report, by clicking Course administration -> Grades . Navigate to Grade administration -> Export -> Plain text file . Export a CSV file using commas as the separator. Open the CSV file you generated. Observe that the first line is a header row, with names for each data column. Pick a subsequent row and completely excise a column from it - not just the data value, but the comma after it as well. Save your CSV file as malformed.csv . Testing with malformed data Navigate to Grade administration -> Import -> CSV file . Upload your malformed CSV file, selecting comma as the separator and with a non-zero number of preview rows. Click Upload grades . Observe that an error message is displayed.