Does the prayer become invalid if the Imam makes a mistake and is not alerted?

If the Imam makes a mistake in recitation during prayer and is not corrected:

- If the mistake is outside of Al-Fatiha, the prayer is valid.

- If the mistake is in Al-Fatiha by omitting one or more verses, or by a grammatical error (laḥn) that changes the meaning, and it is not corrected, then the prayer is invalid.

- Correcting the Imam (al-fatḥ 'ala al-imam) is obligatory in Al-Fatiha, and in other parts if the mistake corrupts the meaning.

- Correcting the Imam is permissible in parts other than Al-Fatiha if the meaning is not changed.