Hello friends, so there is an issue: hundreds of people must enter date time value in to their individual excel workbook, but sometimes they enter it incorrectly.

date time format looks like: yyyy-MM-dd hh:mm

Data validation is not working sometimes because users tend to paste over data validation various random stuff.

The only way can think of is to have an additional cell which will check if a correct data is entered. This check cell should be next to date time cell.

You can easily check for example for a number entry with IF + ISNUMBER functions, but how to check if correct date time is entered I have no idea. Maybe playing with VALUE function?