Is it bad to show a negative message after a positive customer interaction?

Question

Are there any thoughts on how best to tackle the issue of displaying a negative message after a positive customer interaction? Or if it's an issue at all?

I need to display an important negative message even though the customer just completed a positive interaction (added an item to their delivery).

This message notifies the customer whether they will receive their order or not. Essentially, as soon as a customer adds one item to their order it is in an invalid state as it hasn't met the site's minimum spend rules.

Flow 1: Signed in customer has account and payment card set up > they add an item to their order > minimum spend rule not met > delivery not confirmed > invalid order message displayed (min spend not met)

In flow 1 the message is important as the customer will not get their items until their order total is over the minimum spend limit. However, it feels very negative to display this message when the customer is doing something positive (adding items). The message will change to a positive one as soon as minimum spend is met.

Flow 2: Minimum spend limit reached > order confirmed > valid message displayed > customer removes 1 item > minimum spend limit not reached > order not confirmed > invalid order message displayed

In flow 2 the customer has invalidated their order by removing an item that takes them below the minimum spend limit. They need to be made aware of this as their order will not be delivered.

Please note the unusual shopping model: A customer must have an account with a payment card and delivery address stored. They have a specified delivery day each week. They can then add to their order and as long as the minimum spend is met and the card is valid they will receive their items on their delivery day.

Answer 1

Display the order status together with the summary information (typically total, tax, delivery charges, etc. depending on your particular system). But have it start out showing "Minimum spend not met" - in red, with the actual minimum spend requirement included - e.g., "Minimum spend $200.00 not met". Even better to include the actual amount, so the sequence would be something like:

• Minimum spend $200.00 not met, add at least $200.00 of products to complete your order in red
• Minimum spend $200.00 not met, add at least $54.23 of products to complete your order in red
• You have met the minimum spend requirement of $200.00. Complete your order by clicking "Place Order" in green

Plus, the "Place Order" button should be grayed out/disabled until the minimum spend is met.

Answer 2

Rather than an outright explicit error message, why not try changing the interface to reflect the state that it is in.

A very simple and basic example would be that elements in the interface are the color red when the user doesn't reach the spend limit and green/enabled when the spend threshold is met.

Answer 3

You should design two levels of system messages;
a) General - process is confirmed, or not
b) Validation - minimum order is met or not

Validation messages are usually placed close to the fields where the action is performed, and they are smaller.
General messages are larger, always distinguished, like on top i.e.