What is the ruling regarding breaking the fast due to forgetting the obligation of continuity or being ignorant of it, or believing the required sequence was already completed?

Primary text

If one breaks the fast while forgetting the obligation of continuity, or being ignorant of it, or mistakenly believing that the required sequence (of fasting months) has been completed, the continuity is severed. This is because the breaking occurred due to ignorance, similar to one who believed only one month of fasting was obligatory.