We are encountering strange issue while updating date column in SharePoint online excel files.

When the dates are entered using dots in between the date and month( like 21.10 , 18.5),in excel it is displaying as 1/21/1900 and 1/18/1900. This applies for any dates entered using dots between DD and MM. Is this a bug?

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This issue doesn’t occur if the dates are entered using a – (like 21-10,18-5) or writing down the month alphabetically(like 21-Oct, 18-May).


It 's the default behavior that we cannot use dots between day and month in the Data format cell in Excel.

Using dots just performs as a number which add to the date from 1/1/1900.


In Excel, a date is the number of days since 01/01/1900 (which is the first date in Excel). For example, when we enter 18.5, it means 18.5 days since 01/01/1900. So it will be displayed as 1/18/1900 12:00:00PM. So when we enter 21.10, it will be displayed as 1/21/1900 2:24:00 AM.

However, when we enter 21-10 or 18-5, the contents of the cell will be Text and not a number. Excel will not think it's a date. It's easy to distinguish: In Excel, text is always displayed on the left of a cell. A number or a date is displayed on the right.



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