This happens when you enter an invalid date — for example, 31 June or 31 November. The cursor remains in the field until you correct it.
Use the Backspace key to delete back to the incorrect digit, or use the cursor keys to navigate to it.
Delete the incorrect digit and replace it with a valid one.
Press Escape to cancel the transaction entirely.
You cannot use the mouse to move the cursor or leave the field while an invalid date is entered.