If the ma'mum forgets in the prayer something that is a pillar for the validity of the rak'ah, is it made up with a complete rak'ah?

The questioner : If the ma'mum forgets in the prayer something that is a condition for the validity of the rak'ah, such as al-Fatihah, or ruku', or sujud, is it made up with a complete rak'ah, or is sujud al-sahw sufficient?

The Shaykh : No, it must be made up if he is able to return to the forgotten pillar. If he returns to the sujud or the ruku', he returns to that and then continues the prayer.
Al-Halabi : Shaykh, we once asked you, my teacher, about an incident that happened in our mosque, the 'Umar Mosque. Some of the imams hurried in the recitation, so half of the people in the mosque, or many of them, were not able to complete al-Fatihah, even though they were with him from the beginning of the prayer and from the first rak'ah. So they bowed and did not complete al-Fatihah. I answered that day, my teacher, that the imam is responsible for them; he guarantees for them, meaning something like this, or another scenario. I ask for a ruling on it: a person who makes a mistake, meaning he leaves off the sujud, or what is it called? It is a bit difficult to visualize, but a person makes a mistake and instead of reciting al-Fatihah, he recites the tashahhud, for example. He does not remember until he wants to bow. Does the same ruling apply to him?

The Shaykh : Of course, he must return to recite al-Fatihah while standing.
Al-Halabi : Meaning he performs a new rak'ah after he finishes?

The Shaykh : Yes, exactly.
Al-Halabi : What about the one who did not complete al-Fatihah?

The Shaykh : That one is a follower; the imam is responsible.
Al-Halabi : The discussion is about the follower, Shaykh, in all the scenarios.

The Shaykh : I do not think so.
Al-Halabi : The brother says: if the ma'mum forgets, if the ma'mum...

The questioner : I said: if the ma'mum forgets in the prayer something that is a condition for the validity of the rak'ah?
Al-Halabi : Meaning the discussion is about the ma'mum, Shaykh.

The Shaykh : How can he visualize the imam in front of him bowing and prostrating? How?

The questioner : Regarding the scenario of ruku' or sujud, forgetfulness might occur, for example, in the sujud, he prostrates the first prostration, then he makes a mistake by thinking about something or contemplating something, so he does not hear the imam's takbir. He does not hear the imam's takbir, so he raises his head, and the imam is in the tashahhud?

The Shaykh : And this has happened, meaning?

The questioner : In fact, it may have happened to me once.

The questioner : But perhaps ten years ago.

The Shaykh : Perhaps I was thinking about a hadith and its chain of narration. And you were a follower?

The questioner : Yes, and I was a follower.

The Shaykh : It is the same answer, of course. Even if he was a follower, it is the same answer. He must return to the pillar.

The questioner : Meaning he performs a complete rak'ah?

The Shaykh: Yes.