Describes the cause and action for error messages.
Error Message(English)：
data validation not ignoring blanks
Excel Data Validation Tips and Troubleshooting - Contextures
https://www.contextures.com/xlDataVal08.html
Data Validation List With ...
https://www.contextures.com/xlDataVal08.html#symbols
Data Validation Dropdowns ...
https://www.contextures.com/xlDataVal08.html#Change
Missing Arrows
https://www.contextures.com/xlDataVal08.html#ArrowsNotVisible
Ignore Blank Problems in Excel Data Validation - YouTube
https://www.youtube.com/watch?v=_Q1f_FlvwWg
https://www.youtube.com/watch?v=_Q1f_FlvwWg
Excel Ignore Blanks in Data Validation List ? My Online Training Hub
https://www.myonlinetraininghub.com/excel-ignore-blanks-in-data-validation-list
How to use data validation to prevent blank cells left in Excel column?
https://www.extendoffice.com/documents/excel/5317-excel-data-validation-do-not-allow-blank.html
How to create drop down list ignore blank cells in Excel? - ExtendOffice
https://www.extendoffice.com/documents/excel/2445-excel-drop-down-list-ignore-blank.html