Where can I get that javascript override to change the datepicker format? I prefer to have it in MM/dd/YYYY because in the report during the printing, old documents will not show the date.  (I can create a computed field though but takes extra coding).

Hello John,

  Odoo's date format, including the Datepicker, is influenced by the language settings of your user preferences. The default format you're seeing (MMM d) is likely due to the language and locale settings currently applied. To adjust the date format to MM/dd/YYYY, you can follow these steps:

  1. Navigate to Settings > Users & Companies > Users.

  2. Select your user and click on Edit.

  3. Scroll down to the Preferences section and locate the Language field.

  4. Change your language to one that typically uses the MM/dd/YYYY format, or if your preferred language is already selected, you might need to adjust the locale settings directly in the source code or through server settings, as Odoo's frontend date format is tightly coupled with the language preferences.

  5. Save your changes and refresh the page to see the updated date format.

For personalized assistance:
https://www.pragtech.co.in/contact-us-mql.html

We changed the date format in Odoo 19 based on user interface/user experience research showing that including a textual representation of the month is easier and more reliable to interpret than all-numeric formats. It reduces cognitive load on Users.

For any date field or date time field in Odoo 19 you can hover over it to see the traditional format:

Hi,

In Odoo 19, the datepicker defaults to MMM d (e.g., Sep 18) because it uses the Luxon library with localized formats, which can be confusing compared to the old MM/dd/yyyy. You can change this by editing the Language → Date Format in settings, but the picker may still show abbreviated months. The most reliable fix is a small JavaScript override in a custom module to force MM/dd/yyyy everywhere..

Hope it helps