All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Whoever misses an obligatory prayer for some excuse has to make it up later. All the Muslim scholars agreed upon this ruling. There is no difference between Fajr prayer or any other prayer as far as the matter of making up is concerned.
The disagreement is only concerning the one who misses the prayer without any excuse till the fixed time of the prayer expires.
The majority of Muslim scholars, including the four Imams, are of the opinion that making up such Prayers is also compulsory.
Therefore, whoever fails to perform any obligatory prayer at its prescribed fixed time should make it up later.
For more benefit on missed prayers, please refer to Fataawa 162085, 105182, 95419, 127769, 160935 and 334915.
Allah knows best.