Encoding
We recommend using UTF-8 encoded CSV files. Other encodings are accepted but are harder to troubleshoot in case of errors.
In Microsoft Excel, the recommended save format is CSV UTF-8 (Comma delimited) (*.csv), available from File → Save As → File Format. This is the safest option for non-ASCII characters (accents, non-Latin scripts).
Formatting
Most users open and edit CSV files in a spreadsheet program — Microsoft Excel, Google Sheets, Apple Numbers, or LibreOffice Calc. All of these can introduce errors at save time, such as trailing commas added when a column is removed in Excel, or column types being auto-converted (phone numbers turning into scientific notation, leading zeros being stripped).
Tips by tool:
Microsoft Excel — Use File → Save As → CSV UTF-8 (Comma delimited). If you see "this file type only saves the active worksheet," click OK to continue.
Google Sheets — Use File → Download → Comma Separated Values (.csv). Google Sheets exports as UTF-8 by default.
Apple Numbers — Use File → Export To → CSV… and choose the UTF-8 text encoding option.
LibreOffice Calc — Use File → Save As, choose Text CSV (.csv), and select UTF-8 in the export dialog.
If you need to inspect or hand-edit a CSV without a spreadsheet program touching it, use a plain text editor such as Notepad++ (Windows) or any code editor (VS Code, Sublime Text, BBEdit).
Missing headers are also a common issue that can cause formatting errors, ensure all CSV files being uploaded to Edlio contain headers.
Trailing Commas
Trailing commas can be interpreted as extra columns and will cause errors when reading the data. To check, open the file in a plain text editor and confirm that the number of commas in the header row matches the number of commas in each data row. In Excel, if you removed a column and trailing commas were added, the cleanest fix is to create a new empty spreadsheet, paste in your headers and data, and save it again as CSV UTF-8 (Comma delimited).
Extra commas in value fields
If you have a single value that includes a comma, a name like 'John, III' for example, that value needs to be wrapped in quotes to remove the ambiguity between the column separating commas and the one in the value:
Will not work
First_name, Last_name, Student_ID
John, III, Doe, 1234
Works
First_name, Last_name, Student_ID
"John, III", Doe, 1234
Leading zeroes, empty characters, incorrect quotes
Other issues that can cause formatting issues are leading zeroes being removed by applications that evaluate the values as integers, extra or empty characters that are not always visible when skimming the data, and incorrectly formatted quotes such as single quotes or nested double quotes.
Most of the above can occur when copying the data from a differently encoded source or saving your file in an unsupported format.
For more information about the CSV format, see the Wikipedia article on Comma-separated values.