One who does something forbidden and is unaware of the consequences
Question

What is the ruling on a person who does one of the actions that are forbidden in ihraam and is unaware of the expiation that he has to offer if he does that?.
Praise be to Allah.Firstly we should draw attention to the ignorance of many of the pilgrims who perform Hajj and ‘Umrah, which leads them to commit acts that are forbidden in ihraam, or to do acts of worship in ways that are not prescribed. A pilgrim may spend a great deal of money, especially if he is coming from a far-off land, then lose his reward or have it reduced because he is ignorant of what is required of him. 
Hence everyone who wants to perform the rituals must learn the rulings on them before he starts to do them. It was narrated that Anas (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “Seeking knowledge is a duty on every Muslim.” Narrated by Ibn Maajah and others; classed as saheeh by al-Albaani in Takhreej Mushkilat al-Faqar. 
Imam Ahmad said that what this means is that each person must seek the knowledge that he needs, namely how to do wudoo’ and pray, how to pay zakaah for those who have wealth, and how to do Hajj etc. (Jaami’ Bayaan al-‘Ilm by Ibn ‘Abd al-Barr, 1/52). 
Al-Hasan ibn Shaqeeq said: I asked ‘Abd-Allah ibn al-Mubaarak: How much knowledge should people seek to acquire? He said: No one should start to do anything without knowledge; he should ask and learn. This is what people have to do with regard to acquiring knowledge. (al-Faqeeh wa’l-Mutafaqqih by al-Baghdaadi, 45). Hence Imam al-Bukhaari (may Allah have mercy on him) included a chapter in his Saheeh entitled: Baab al-‘ilm qabla al-‘qawl wa’l-‘aml (Learning before speaking and acting).
 This does not mean that everyone has to memorize by heart a book that discusses the rituals of Hajj, rather what every Muslim must do is to learn whatever he needs to know, according to his situation, either by himself, if he is qualified to do so, or by asking scholars, or by accompanying someone who can show him what to do and teach him whatever he should do whenever he needs to know. 
With regard to the things that are forbidden during ihraam, these have been explained in the answer to question no. 11356. 
But if a person does one of these things out of ignorance that Allah had forbidden that when one is in a state of ihraam, then he does not have to do anything (i.e., offer fidyah etc), because Allah says (interpretation of the meaning): 
“And there is no sin on you concerning that in which you made a mistake, except in regard to what your hearts deliberately intend. And Allah is Ever Oft‑Forgiving, Most Merciful” [al-Ahzaab 33:5]
But if he knew that this thing he did is one of the things that are forbidden when one is in a state of ihraam, but he did not realize the consequences of this action, then Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:  
This is not an excuse, because a person is excused if he was unaware of the ruling and did not know that this thing is haraam. As for the one who was unaware of the consequences of doing this action, that is not an excuse. Hence if a married man knew that zina is haraam, and he is an adult of sound mind and he was married or previously-married, but he went ahead and committed zina, then he must be stoned. If he says, ‘I did not know that the hadd punishment (for zina) is stoning, and if I had known that the hadd punishment is stoning I would not have done it,’ then we say to him that this is not an excuse, and you must be stoned, even if you did not know what the consequences of zina are. Hence when the man who had had intercourse during the day in Ramadaan came to the Messenger of Allah (peace and blessings of Allah be upon him) to ask him what he should do, the Prophet (peace and blessings of Allah be upon him) told him that he had to offer expiation, even though at the time when he was having intercourse he was unaware of what he would have to do. This indicates that if a person commits a sin and transgresses the sacred limits of Allah, then he must face the consequences of that sin, even if he did not know of its effects when he did it. 
Al-Fataawa 22/173-174.