Final Fantasy XV has some missable content that can only be accessed within certain chapters. Some content may be missed due to bugs, or due to the content no longer being available.
General[]
Due to a bug in the game, learning a new recipe will sometimes fail to trigger. Usually, this can be corrected by fulfilling the criteria again. However, some recipes are learned from Iron Shelf Recipe books that are purchased from shops. These are key items that cannot be sold and are retained in New Game Plus, so if Ignis does not learn the recipe as soon as the item is purchased, he will never be able to learn it, even when starting a New Game Plus. Thus, the best course of action may be to load a previous save and try buying the book again.
The Engine Blade and other upgradeable weapons were made sellable in patch 1.03. If the player sells them, they cannot be upgraded, permanently missing out on the upgraded versions until New Game Plus (or chapter select).
It is not possible to complete the bestiary in a single fresh playthrough. There are two "Cup Noodle" quest enemies (Rogue Behemoth for selecting "Meat" and Rogue Karlabos for selecting "Shrimp"), and the player can only fight one of them since the quest is not repeatable. The player will need to use New Game Plus or chapter select to redo the quest.
Tours are not repeatable (apart from the "Liege of the Lake", which can be done until the player catches the fish), and thus if the player wants the "success" version of a tour, they must get it on the first attempt. However, succeeding or failing does not affect the tour's rewards or anything else in the game.
Photo op missions cannot be repeated. If the player wants a certain party setup for a photo op, the player must not complete it until the desired guest character is part of the party. There is a rare chance of Gentiana appearing in a photo op, but only if the mission is done in Chapter 5 or later.
The sidequest "Let Sleeping Mountains Lie" is first available in Chapter 9. When the player goes to Longwythe Rest Area to meet Dave, Noctis will see up to 14 of the allies he made throughout Lucis and get items from each of them. The allies that appear depend on whom the player has met already. Since Ezma is not available until Chapter 15, this part of the quest must be held off until then to see all allies. This also holds true for returning to Longwythe after defeating the adamantoise.
The Moogle Chocobo Carnival and the Final Fantasy XV: Assassin's Festival events are no longer available. The unique Medjay Assassin's Shield and Medjay Assassin's Robe cannot be acquired, and only remain in save games that completed the Assassin's Creed event when it was available.
Chapter by chapter[]
Chapter 2[]
The bestiary entry for Magitek Bannerman (level 6 variant) is missable.
Chapter 3[]
The bestiary entry for Magitek Bannerman (level 18 variant) is missable.
The quest "Pilgrimage" cannot be completed if it is not finished before the story moves to the Disc of Cauthess in Chapter 4. If it is active but incomplete, it will disappear from the player's quest log.
The quest "Photo Op: Disc" can never again be triggered if it is not initiated before the party visits the Disc of Cauthess in Chapter 4. As long as it is accepted before then, it can still be completed afterwards.
Chapter 4[]
When Ardyn Izunia asks to stop at a caravan in Coernix Station - Cauthess, it is is only opportunity to see a lodging scene with him. It is also the only chance to hear him comment on Prompto's photos.
Missable cutscene.
The morning after resting in a caravan with Ardyn, listening to the NPCs here will trigger a missable cutscene of Lunafreya Nox Fleuret's work as the Oracle.
The Disc of Cauthess cannot be revisited. Anything the player wants to do in the dungeon must be finished on the first visit.
Chapter 6[]
Any photo ops that the player wants to include Iris Amicitia in must be done in Chapter 6. Any camping or lodging scenes that include Iris can only be seen while she is with the party. Iris's Eclipse technique can only be mastered while she is with the party in Chapter 6. It maxes out at level 2.
Chapter 7[]
Aranea poses for a group photo.
The quest "Photo Op: Lakefront" is the only photo op that can be done without Gladiolus. It is also the only photo op that can include Aranea Highwind. Any camping or lodging scenes that include Aranea can only be seen while she is with the party. Aranea's Highwind technique can only be mastered while she is with the party in Chapter 7.
Chapter 8[]
If the player does not talk to Cor Leonis before boarding the royal vessel at the end of Chapter 8, they miss out on a Magic Flask.
Chapter 10[]
The locations in Chapter 10 cannot be returned to, so anything the player misses cannot be revisited.
The bestiary entries for Falxfang and Gurangatch are missable.
There are two missable datalogs (both in the "Almanac" section) in Chapter 10.
The quests "Chocobaby Roundup" and "Caestino on Camera" must be completed before departing Cartanica.
There is a brief missable cutscene when the player camps at the haven in Fodina Caestino.
Camping at the haven provides a recipe for Chilled Food Tin, which is missable.
Chapter 11[]
The locations in Chapter 11 cannot be returned to, so anything the player misses cannot be revisited.
Chapter 12[]
The locations in Chapter 12 cannot be returned to, so anything the player misses cannot be revisited. There are three missable datalogs (one in the "Cosmogony" section, and two in the "Almanac" section) in Chapter 12.
Chapter 13[]
The locations in Chapter 13 cannot be returned to, so anything the player misses cannot be revisited.
Noctis's route in Chapter 13 must be completed during the chapter. Gladiolus's route can be done from the title screen after completing the game.
The bestiary entry for Haywire Axeman is missable.
There are 17 missable datalogs (three in the "Letters" section, eleven in the "Reports" section, and three in the "The Ω-Files" section) in Chapter 13.
Chapter 14[]
The locations in Chapter 14 prior to reaching Insomnia cannot be returned to, so anything the player misses cannot be revisited.
A camping scene involving Noctis alone can only be seen during this chapter Lachyrte Haven west of Galdin Quay. Camping there is also the last chance to get the Chilled Food Tin recipe.
There are two missable datalogs (both in the "Reports" section) in Chapter 14, both located at Hammerhead.
In the standard edition of the game, the Hyperion greatsword and Quicksilver gun can only be obtained in Chapter 14. Gladiolus and Prompto come equipped with them when they join. Additional ones can be purchased at weapon dealers in Hammerhead. They are not missable in the Windows and Royal Editions since they can also be purchased at the Kingsglaive Base Camp.
Extended scene after Cerberus boss battle.
In the Windows and Royal Editions, the player needs to complete all three side quests from the Kingsglaive Base Camp ("Crown City Without a King", "A Glaive out of Time", and "Relics of the Empire") to get an extended scene for the Cerberus boss. After defeating the Cerberus, the player needs to pick up the Trihead Heart from the floor before leaving the area.
Depending on which photo the player chooses as their "Certificate of Completion" at the end of the game, the party will make different comments. To hear all comments, the player needs to have enough different types of photos saved. Whichever photo the player selects is permanent and cannot be changed.
DLC[]
Final Fantasy XV: Episode Gladiolus[]
Once Gladiolus reaches the soul at the end of each stage of the trial, it is not possible to go back to any earlier areas.
Final Fantasy XV: Episode Prompto[]
The first Niflheim facility cannot be returned to once left, so the items and photo ops there are missed until a replay if the player doesn't find them.
Four documents and six audio logs from the the Niflheim facility can be permanently missed.
Final Fantasy XV: Episode Ignis[]
It is not possible to return to earlier chapters after moving on to a new one. All documents, cooking utensils, and outfits from the first chapter cannot be obtained once Ignis reaches the second chapter.
Final Fantasy XV: Episode Ardyn[]
It is not possible to return to earlier chapters after moving on to a new one. The documents in the base cannot be obtained once the player gets full control of Ardyn in Insomnia.
Final Fantasy XV: Comrades[]
It is only possible to obtain one copy of some weapons not found in shops or dropped by enemies. If the player sells them, they cannot get another copy unless with New Game Plus.
Once the leader of an outpost is elected, they cannot be changed, and the bonus from that leader is permanent.
Once Chocobo Stables access is granted, the starter black chocobo cannot be released. The training given it is permanent, so if the player fails to get it to its maximum level (70), it will never reach its full potential.
If Kain's Lance is dismantled, it will become a Dulled Spear. While it is possible to craft the Dulled Spear back into Kain's Lance, the upgrade requirements limit the player's options for improving its stats.