What is the ruling on fasting the Days of Tashreeq out of ignorance of their prohibition? And is it obligatory to make up the days that were fasted?

The preponderant opinion among scholars is that it is not permissible to fast during the Ayyam al-Tashreeq except for the pilgrim performing Tamattu' Hajj who does not find a sacrificial animal. Fasting these days does not count as a make-up for other fasts. Similarly, it is not permissible to fast on the days of Eid al-Fitr and Eid al-Adha, due to the prohibition of the Prophet, peace and blessings be upon him, from fasting on them, and fasting on these days does not count as a make-up.