You can't change the sales order date because there is a delivery note which is based on the sales order and changing the date would destroy the referential integrity of the two records.
The best solution would be to cancel the delivery note(s), then go back into the sales order, change the date, and then re-deliver the delivery notes.
Also, there is a warning message prompt that appears when entering the wrong required date in the sales order, which is sufficient to warn you not to enter an invalid date:
The requirement date entered is before today's date.
Wrong required date in sales order
I created a sales order that's got an incorrect date required. 0024 is entered rather than the year 2024. The problem is one one of the products has already been action, so the status is green.
J
Written by Jes Foxall-Beckley
Updated today