If there is only a small mistake that is only spelling mistake or any error in middle name, then it will not cause any hindrance during admission to IIT/NIT. But if there is a bigger error then it may cause some problem during admission to NIT/IIT. However, since board criteria is removed for IITs admissions, it may not cause any problem during IIT admission but may cause some problem during admission to one of the NITs on the basis of JEE score.

However, you may try contacting your respective board for correction, if allowed.

Hope it helps.