One day, someone decides to create a work of fiction which turns out to be a huge success. To cash in on its success, numerous spinoffs and licensed material might be produced that are centered on that particular work, with many of them claiming to be canonical with the original work.
But then from out of nowhere, the creator decides to produce their official follow-up which flat-out contradicts what happened in the spinoff material. Looks like the writer of that one tie-in book was too hasty with killing that seemingly unimportant character. Or they incorrectly predicted how the aftermath of the original story would turn out. Alternatively, spin-offs or other additional material created for an on-going Long Runner is eventually contradicted when the original work visits the same subject. In the case of an anime contradicting the on-going manga it's adapting, it's common for the anime to outright ignore their version and pretend it never happened.
This usually happens because the creator is unaware of the spinoff material (after all, it may have faded into obscurity during the Sequel Gap) or because they have deliberately chosen to retcon the spinoff out of existence, or there was simply miscommunication between the creator and the tie-in writers. When it comes to fandom if this happens, at best it'll just be considered an Alternate Continuity. Avoiding this trope is often the reason why Filler material has so little substance to it.
Compare Series Continuity Error, where two or more installments of the same branch of a franchise unintentionally contradict each other. See also Early Installment Weirdness and Continuity Snarl. Often results in Characterization Marches On when a character from the original work ends up behaving differently in the followup than they are depicted in the spinoffs. Not to be confused with Schrödinger's Canon, where there's still a chance that the spin-off in question might be considered canonical. The Fanon counterpart to this trope is Outdated by Canon, and for mere fan theories it's Jossed.
- Any portrayal of the Space Jockeys (now known as Engineers) in the Alien, Predator, or Alien vs. Predator expanded universe prior to the release of Prometheus is guaranteed to fall under this trope, such as the Xenomorph-Space Jockey hybrid in the comic Aliens: Apocalypse and in the game Aliens: Infestation.
- Given that Incredibles 2 leads off with fighting and defeating the Underminer and then goes into Helen becoming family breadwinner and Bob adapting to being a House Husband, I2 ignores the comic adaptation and the Rise of the Underminer game in favor of only needing the audience to be familiar with the previous film (and, optionally, its spin-off, Jack-Jack Attack).
- The Mortal Kombat comics by Malibu depicts Noob Saibot as a separate entity from the original Sub-Zero, who unlike the games, survives the first tournament and doesn't die until the second one. The true identity of Noob Saibot as the original Sub-Zero was not established in the games themselves until Mortal Kombat: Deception. Furthermore, the live-action TV series Mortal Kombat: Conquest took it even further by having Noob Saibot as an Outworld warrior who co-existed alongside Sub-Zero's ancestor during the Great Kung Lao's lifetime, which would make him over hundreds of years old during the present time of the games.
- The original Star Wars Expanded Universe (now known as Star Wars Legends) was loaded with decades of comic books, video games, TV shows, etc. that sometimes contradicted each other and the movies themselves in some way, contributing to Disney's decision de-canonize much of it and rebuild the EU more or less from the ground up following their acquisition of Lucasfilm.
- A great example is the first piece of EU/Legends fiction, the novel Splinter of the Mind's Eye, which was published between A New Hope and The Empire Strikes Back. It was intended as a possible TV Movie canonical sequel by Lucas in the event that A New Hope didn't pan out. Amongst other things, Luke and Leia are implied to have a budding romantic/sexual relationship, and Luke is portrayed as a Lovable Rogue with a knack for lying.
- George Lucas tried to prevent this with the Clone Wars by forbidding any direct depictions/discussions of it in EU works, having always intended to tell that particular story himself eventually. It didn't entirely work; while there were only vague allusions made prior to the release of Attack of the Clones, it is clear that a lot of the writers of those allusions assumed that the Clone Wars entailed the Jedi and Republic fighting an evil army of clones, rather than fighting alongside a heroic army of clones. Most notable in this regard is The Thrawn Trilogy, which not only makes this flub, but also contains some other tidbits that ended up being cut or reworked in later stories, such Coruscant not being a City Planet or Darth Vader having lost his right arm as punishment for the Death Star's destruction.
- The Rise of Skywalker ignores Poe having encountered jumptroopers earlier in Star Wars: Poe Dameron, the destruction of the Lars moisture farm in Star Wars: Darth Vader, and Luke's X-Wing being non-operational in The Last Jedi Visual Dictionary.
- A lot of the Filler in Dragon Ball and Dragon Ball Z that tried to expand on the lore of the setting eventually got invalidated as the manga and overall Dragon Ball franchise continued along:
- The earliest example is a Red Ribbon Army episode where Master Roshi recounts the legend of the Dragon Balls that explains their origin (they were originally one enormous wish-granting gem that, after years of greedy pillaging to obtain it, were split into the seven balls by the Dragon God). A year and a half later Toriyama would introduce his own backstory with the Guardian of Earth, Kami (God) as their creator.
- Another Red Ribbon example is Dr. Frappe, who is introduced in the anime as the creator of Android #8. Four and a half years later Akira Toriyama brought the Android line back and introduced their creator, Dr. Gero, disregarding Dr. Frappe entirely.
- During Gohan's training in the Saiyan Arc, Gohan goes wild and attacks Piccolo thanks to subconscious commands sent from Goku's Saiyan pod, so Piccolo obliterates it. Only a month later, the manga would have Goku use this pod as the basis for a spaceship that takes him to Namek.
- During Goku's training with King Kai in the same arc, he's told the full story about the death of the Saiyans: their homeworld's destruction by a meteor was in fact a karmic act by the planet's Guardian. Three months later, the manga would contradict this by explaining that new villain Frieza had destroyed it himself for entirely selfish reasons, and that the original chance meteor story was a lie of his to keep the surviving Saiyans loyal to him.
- After the new Frieza destruction backstory was revealed, Toei made a TV special depicting the last stand of Goku's father Bardock as he realizes Frieza will destroy it, which Toriyama liked enough to give Bardock a cameo when Goku finally met Frieza. This would be contradicted by Dragon Ball Minus in Jaco the Galactic Patrolman, with Toriyama giving these events a different take where Goku is sent away deliberately and Bardock is a softer character. This would be solidified in Dragon Ball Super: Broly, which incorporates Minus as part of the opening backstory scene.
- King Kai's exposition also explained that the Saiyans were cavemen who settled on planet Plant and renamed it after their king Vegeta, with Plan to Eradicate the Saiyans and Dragon Ball GT elaborating that they slaughtered the native Tsufuru/Tuffle people and seized their technology in the process. This would later be overwritten by Dragon Ball Super, establishing that the Saiyans were always on their homeworld (originally named Sadala) with no Tsufruians, and remained somewhat primitive. The Broly movie also suggests that King Cold took them into his service three generations before Freeza destroyed the planet, rather than Frieza himself doing this just one generation earlier.
- Speaking of Broly, while his three movies could comfortably fit into the original story even today, in 2018 Dragon Ball Super: Broly would come out that completely reinvents his characterization and his first meeting with Goku and Vegeta, which now takes place much later as an unambiguously canonical story.
- The anime adaptation of Saint Seiya introduced several elements that contradicted the Manga. The most noteworthy example would be Hyoga's master. The manga introduced a Canon Foreigner called the Crystal Saint as his master, only for the manga to reveal that it was actually Aquarius Camus. The Anime tried to patch this over stating the Camus was the master of Crystal Saint.
- Gundam: Yoshiyuki Tomino wrote a novel called Gaia Gear, which operates on the assumption that nothing of relevance happened for nearly 200 years following the events of Char's Counterattack. Needless to say, several sequels like Gundam F91 and V Gundam were produced (some of them with Tomino's involvement) which contradict this, and while Gaia Gear hasn't officially stricken from canonicity there's no way it can fit into the timeline anymore.
- GirlsundPanzer has the Ribbon Warrior manga spinoff which began prior to the release of Der Film and Das Finale. As a result, the manga has several divergence with the main storyline, especially in regards to how BC Freedom High School was handled.
- Haruhi Suzumiya: Emiri Kimidori's Image Song, which was released before the tenth volume of the light novel series, paints her as someone who wants to connect with humans and make friends but can't due to being a humanoid interface. However, the tenth volume reveals that she's actually largely indifferent to humanity and refuses to do anything that isn't ordered by the Entity, not even when her fellow interface Yuki's personal safety is at risk.
- My Little Pony: Friendship Is Magic (IDW): Effort was made to keep the comic stories and events in line with the canon of the animated series — according to the comic artist Andy Price, the "comics are canonical until [the] show contradicts [them]" according to Hasbro — and most that fans would point out were just minor details that could be glossed over. However, the show contradicting the comics is something that has happened fairly often, overriding both stories as a whole and important details of other ones.
- My Little Pony: FIENDship Is Magic: The Dazzlings issue covers their backstory and how they came into the human world to be the villains of Rainbow Rocks. However, in the seventh season, a different and incompatible account of how this happened is shown and scrubs away the comic's canon.
- "Reflections": The story's setup involves Celestia and Starswirl having adventured to parallel realities in the wake of Nightmare Moon's banishment by using the magical mirrors Starswirl had created, until Celestia fell in love with an alternate version of Sombra and Starswirl closed off the mirrors to prevent excessive cross-universe entanglements. The Season 7 finale, "Shadow Play", however establishes that Starswirl had vanished when Luna and Celestia were still children and before they became the rulers of Equestria, requiring him to have been long gone when Luna became Nightmare Moon and making it impossible for him to have played the central part he did in the comic's backstory.
- "Seige of the Crystal Empire" has the return of King Sombra, who was supposedly killed off at the start of season three. The writers of the comic assumed the TV writers were done with him, and so brought him back with both a backstory in the aforementioned "Fiendship is Magic" mini-series as well as resurrecting him for the arc. Fast forward a few years to the show's final season and Sombra is revived at the start of the season and acts as the villain for the first two episodes, completely ignoring the comic's story.
- The Infinite Loops has a handy explanation for this: expansions and variant loops. See, the unknown disaster that caused the loops forced most of the multiverse to re-start from backups — i.e. their media in our world. Because of this, anything that isn't explicitly stated in canonicity varies from loop to loop (i.e. the Walled Kingdom shifted locations frequently because the canonical world map of Attack on Titan was only revealed later and is a spoiler to boot, and Gilda's backstory was usually something very different from Griffonstone). Loops sometimes get 'expansions' (i.e. continuations of the media) that can stabilize more of the loop — which, out of universe, is the writers taking new canonicity into account. It's usually fairly well-worked in, with stories of loopers coping with baseline deaths and the loss of what they considered their childhoods.
- Avatar: The Last Airbender fanfic The Children of War. In the final chapter Ursa discovers that she is secretly the daughter of Avatar Sozin, and is warned to not let the Fire Nation Royal court know. In Avatar: The Last Airbender The Search Ursa is fully aware of her heritage, as does the Fire Nation as it is the very reason Oazi marries her.
- Alien: Covenant puts the final nail in the coffin of the Alien vs. Predator films by revealing the xenomorph, as we know it, didn't exist until the events of Alien: Covenant, as they were created by David mucking about with Engineer biotech.
- Dumb and Dumber To ignores plot details from the prequel, When Harry Met Lloyd, and the animated series where Harry and Lloyd go on further adventures with the Mutt Cuts Shaggin' Wagon and their pet beaver Kitty.
- Ghostbusters: Afterlife ignores the animated series and video game continuations of the films, as paranormal activity hasn't been reported in thirty years.
- Godzilla, Mothra, King Ghidorah: Giant Monsters All-Out Attack! and Godzilla: Final Wars reference Godzilla (1998), ignoring Godzilla: The Series where Zilla returns as a cyborg and the Godzilla hatchling grows up to fight additional monsters.
- The Jurassic Park films have ignored the video games and comics, despite being promoted as official continuations of the story.
- Men in Black II ignores the animated series where Agent J and Agent K continue to have adventures, and follows the ending of the first movie instead.
- Pirates of the Caribbean: According to prequel books, Jack Sparrow used to work for the East India Trading Company and was made captain of the Wicked Wench, until he refused to transport slaves, resulting in Cutler Beckett branding him a pirate and sinking his ship (which would later become the Black Pearl thanks to Jack's deal with Davy Jones). The movie Pirates of the Caribbean: Dead Men Tell No Tales however shows Jack becoming a pirate captain after inheriting both his magic compass and the Wicked Wench during a fierce battle against the pirate hunter Armando Salazar, and cementing his position as captain by defeating Salazar.
- The Saw franchise received a prequel comic book titled Saw: Rebirth to tie into the release Saw II, which detailed the backstory of John Kramer and was considered canon by the films' writers at the time. Saw IV, which brought a new writing team to the franchise, rendered the comic incompatible with the film canon due to the new writers making a drastically different version of John's backstory as one of the film's main storylines. This new backstory would be further built upon in later films.
- The Terminator films ignore the expanded universe materials, including novels, the Future War toyline, the TV series, the ride, and the origin story introduced in a crossover.
- TRON: Legacy ignores TRON 2.0 and the tie-in comics.
- The X-Men Film Series ignores plots introduced in the tie-in comics and video games, this caused problems since many of them tried to fix plot holes introduced in the film series, which is loaded with them, but removing these spin-offs from continuity meant those plot holes were opened again.
- Given that Incredibles 2 leads off with fighting and defeating the Underminer and then goes into Helen becoming family breadwinner and Bob adapting to being a House Husband, the film ignores the comic adaptation and the Rise of the Underminer game in favor of only needing the audience to be familiar with the previous film (and, optionally, its spin-off, Jack-Jack Attack).
- The Lion King: Six New Adventures was a series of licensed book sequels based off of The Lion King. They starred Simba's son Kopa and gave info on things like Simba's grandparents and Scar's youth. Come the direct-to-video sequel The Lion King II: Simba's Pride and Kopa has been replaced with a daughter named Kiara. The series The Lion Guard also features a different backstory for Scar (and, though it acknowledges that he had a different name once, it doesn't outright call him "Taka"), though whether the cartoon is canonical to the films or is in an Alternate Continuity is up for grabs.
- The Journal of the Two Sisters is a companion book for My Little Pony: Friendship Is Magic written by one of the show's writers. The canonicity of the book has been pulled into question due to inconsistencies with later episodes of the show. For example, the book states that other alicorns existed in the past and it's heavily implied Celestia and Luna were born alicorn. Season 6's "The Crystaling" implies that Flurry Heart is the first alicorn ever born in Equestria. The book's writer - who doesn't work on the show anymore - tries to handwave this as the sisters being born before Equestria. The episode "Shadow Play" also strongly counters the book by depicting the Tree of Harmony as younger than the book does.
- Older Than Steam: After Cervantes wrote Book I of Don Quixote, an unknown writer using the pseudonym of Avellaneda published a second part, wholly without Cervantess permission. This spurred him to write the proper sequel, in which Avellanedas volume exists in-universe, and causes the real Quixote to have a breakdown when he discovers it, since he knows he didnt do anything described within it.
- The Young Adult Buffy the Vampire Slayer book Halloween Rain, the third Buffyverse book ever written, has Buffy fighting for her life during All Hallows Eve, when the forces of evil are at their strongest. Days before its release, the show had its own Halloween episode — which established that not only is there nothing particularly supernatural about Halloween, but most demons actually take the night off, making it the most normal night in Sunnydale.
- 007 Legends, which is a tie-in to Skyfall, features a level loosely based on the film On Her Majesty's Secret Service, where Daniel Craig's incarnation of James Bond meets and confronts Ernst Stavro Blofeld. This is contradicted by Spectre, which has Craig's Bond meet Blofeld for the first time.
- Castlevania: Circle of the Moon began development as a standalone Gaiden Game separate from the series's main timeline, but as its storyline was not explicitly contradicted by the main series, it wasn't impossible for its events to have taken place after all... that is until Order of Ecclesia was released, its events occurring within a similar time period as Circle of the Moon and thus making it extremely difficult for the two to occur in the same continuity.
- NetherRealm Studios has a tendency to ignore content not directly created by them even if they had their creative guidance and/or approval.
- Injustice: Gods Among Us had a prequel comic book series written by Tom Taylor showing us in detail how this game's version of the DC Universe ended like it is and revealing the fate of characters not addressed in the game. However, the sequel Injustice 2 ignores and/or changes various details from the comic very blatantly (such as the reason of Robin/Damian Wayne's defection to Superman's side, the fate of the Teen Titans (who were alive but imprisoned in the comic but are stated to be dead in the game), and the characterization of some characters such as Poison Ivy (who had a soft spot for Harley in the comic but attempts to coldly kill her in the game's story mode) among many other details).
- Mortal Kombat X and its sequel Mortal Kombat 11 ignores the tie-in comic book series' events and characterization of the characters.
- Disney's Stitch: Experiment 626 was a prequel game released just two days before the original Lilo & Stitch film was released, showing the lives of Dr. Jumba Jookiba and Experiment 626 (Stitch) before their arrest, with 626 collecting DNA for Jumba to use for making more genetic experiments. However, Lilo & Stitch 2: Stitch Has a Glitch had a flashback scene that retconned the game out of the canon, establishing that Jumba and 626 were arrested just shortly after the latter's creation.
- In the Ultima series, the latest game tends to reflect the status quo, becoming more noticeable in Ultima VIII and Ultima IX, where the character customization options are no longer available and it turns out the protagonist has always been a blonde haired human male, ever since the days of Sosaria according to Ultima Online.
- Spider-Man: The New Animated Series, which was an animated follow-up to the first Sam Raimi Spider-Man film, depicts Dr. Curt Connors becoming The Lizard, and then seemingly falling to his death. These are never brought up in Spider-Man 2 or Spider-Man 3, which came out after the series finished its run and feature Dr. Connors alive and well.
- Iron Man: Armored Adventures had one singular promotional comic with two stories. One featured Iron Man battling the Living Laser, which didn't get contradicted. The other, featuring S.H.I.E.L.D. agent versions of Hawkeye and Black Widow, did get contradicted by the show, which introduced them as criminals (at first). Interestingly, the Black Widow in the comic is blonde, so you could argue that it's supposed to be Yelena Belova as opposed to Natasha Romanova, but Hawkeye is explicitly identified as Clint Barton in the comic.