This error occurs while importing slogans, if Q++Studio notices that a Month-Day pair has been repeated.
Common causes are
•Importing a text file with over 366 lines.
•Importing a text file into a non-empty slogans set, where the total number of entries is more than 366.
•Confusion about how the Month-Day slogans set type functions.
For more details, see importing month and day slogans from Excel.
Topic 108736, last updated on 18-Jan-2022