Why is my minimum quantity rule causing a permanent error?

Short answer: the rule’s Min and Max leave no quantity that is also a multiple of Quantity increments, so no cart can pass.

What your customers see on the storefront.

A Quantity Increment rule checks two things at once:

1. The quantity is a multiple of Quantity increments.
2. The quantity is between Min and Max.

If no multiple falls inside that range, the customer sees “Rule Quantity Increment: Not Satisfied” for every quantity, and the checkout button stays locked.

Quantity increments	Min	Max	Valid quantities	Result
6	6	60	6, 12, … 60	Works
6	7	empty	12, 18, …	Works
6	6	10	6	Works, only 6 is allowed
6	8	11	none	Error on every quantity

Fix

1. Set Min to a multiple of Quantity increments, for example 12 for an increment of 6.
2. Leave Max empty if you do not need an upper limit.
3. Save the rule and reload the storefront.

Note

The app checks that Min is at least the increment and below Max, but it does not check that a multiple fits in the range. Test the rule on your storefront after saving.