10/09/2017 becomes 09/10/2017

Hello,
in the cell B3 of this spreadsheet
link text

I insert 10/09/2017 and when I press Enter it becomes 09/10/2017.
The problem has arisen in the last 2 packages (Libreoffice 64 bit for windows)

And what is the problem actually? The behavior corresponds to the date format. Change the date format and/or language in the cell properties dialog.

ok now I know. Anyway I’ve been using this spreadsheet for a few years, always updating LibreOffice to the latest version, and I’ve never had this problem.

Maybe you switched the default locale on your system, for example from it-IT to en-US. The cell B3 is formatted to Italian (Italy) date GG/MM/AAAA (which is translated of DD/MM/YYYY); if your system is now en-US and the work locale is set to default (following the system locale) then likely your Date Acceptance Patterns contain M/D/Y so input is accepted as Mike explained but displayed differently.

You need to check two items:

  1. Date acceptance patterns (under OptionsLanguage SettingsLanguages): this setting allows program to understand which strings must be treated as dates, and parts of those strings mean what. I.e., an acceptance string like M/D/Y allows program to see that a string having three numeric parts separated by forward slashes is an accepted date, and in that date, month is the first part, then goes day, and then year. So it converts the entered matching string to a date with those parts (which is internally a number), and write the resulting number to a cell’s value.
  2. Cell format’s Format code: it tells the program how to display cell’s value. So in case of a format code like DD/MM/YYYY, Calc would know that a number in this cell must be shown as date, and the day of the date must be shown first, then month, then year.

As I shown above, it’s possible for these two settings to be out of synchronization, thus interpreting your input in one manner, and show it back in another. Correct them to be in accordance.