At first glance, Harry Potter fans may seem like a bunch of loveable nerds, enthralled by the world of wizardry and witchcraft. But let me give you a piece of friendly advice: don't cross them.

Warner Bros. Pictures may be about to find this out the hard way, with rumours flying that scriptwriters have made a massive error with a beloved Potter character in the new Fantastic Beasts and Where to Find Them film.

The announcement that Minerva McGonagall would appear in Fantastic Beasts: The Crimes of Grindelwald - played by Fiona Glascott - should have thrilled viewers. However, it did exactly the opposite when they figured out that her arrival may have broken the Potter canon.

The new movie is set in 1927, but angry fans believe that the Hogwarts professor wasn't actually alive at this point in time in the magical universe, so technically shouldn't be in the film.

It is thought that McGonagall was born in 1935, meaning that she shouldn't even exist in 1927, let alone be a witch in her 30s who teaches at Hogwarts.

According to Potter history, the esteemed witch was a registered Animagus who attended Hogwarts from 1947 to 1954, where she was sorted into Gryffindor House.

After finishing her education, Minerva worked for two years at the Ministry of Magic. However, she was left disgusted by the anti-Muggle prejudice she encountered, so after two years, in 1956, she returned to Hogwarts, where she became the person we first met in Harry Potter and the Philosopher's Stone: Head of Gryffindor House and Transfiguration professor.

After doing the maths, disappointed fans took to social media to express their feelings on the break of canon.

Twitter user @eruditechick named the move "inexcusable", writing: "I hate this s**t. What possible excuse is there for it??? I just. Fantastic Beasts: Professor McGonagall Breaks Harry Potter Canon (sic)".

She was joined by @Meliachipics who named the situation "ridiculous". "I know JKR is bad at math but this is ridiculous. How is the biography she wrote 4 years ago about McGonagall and how she was a student under Dumbledore fits with mcgonagall being a professor in 1927?!?, (sic)" she wrote.

However, other viewers were more forgiving, with many of them advising people to wait and see the film before they cast judgement, also pointing out that it was possible McGonagall would appear in a flashforward.

Others fans online were keen to remind people that McGonagall owned a time turner, meaning that she could have easily been present at any point in time.

Twitter user @Riz27256832 reassured fellow Potterheads, putting: "Casting McGonagall in #FantasticBeasts makes sense!!! Who held the Time Turner device from Harry Potter and the Prisoner of Azkhaban before passing it to Hermione Granger... Its Professor McGonagall. Am I right @jk_rowling ? (sic)"

@DerMonarch backed up this idea, writing: "Ugh, the idiots among the Potterheads are at it again... So apparently some actress was revealed to play a "Professor McGonagall" in Crimes of Grindelwald and of course they are immediately assuming Rowling is retconning her own timeline or McG's backstory."

So, will the Harry Potter canon be broken? Watch this space.

At first glance, Harry Potter fans may seem like a bunch of loveable nerds, enthralled by the world of wizardry and witchcraft. But let me give you a piece of friendly advice: don't cross them.

Warner Bros. Pictures may be about to find this out the hard way, with rumours flying that scriptwriters have made a massive error with a beloved Potter character in the new Fantastic Beasts and Where to Find Them film.

The announcement that Minerva McGonagall would appear in Fantastic Beasts: The Crimes of Grindelwald - played by Fiona Glascott - should have thrilled viewers. However, it did exactly the opposite when they figured out that her arrival may have broken the Potter canon.

The new movie is set in 1927, but angry fans believe that the Hogwarts professor wasn't actually alive at this point in time in the magical universe, so technically shouldn't be in the film.

It is thought that McGonagall was born in 1935, meaning that she shouldn't even exist in 1927, let alone be a witch in her 30s who teaches at Hogwarts.

According to Potter history, the esteemed witch was a registered Animagus who attended Hogwarts from 1947 to 1954, where she was sorted into Gryffindor House.

After finishing her education, Minerva worked for two years at the Ministry of Magic. However, she was left disgusted by the anti-Muggle prejudice she encountered, so after two years, in 1956, she returned to Hogwarts, where she became the person we first met in Harry Potter and the Philosopher's Stone: Head of Gryffindor House and Transfiguration professor.

After doing the maths, disappointed fans took to social media to express their feelings on the break of canon.

Twitter user @eruditechick named the move "inexcusable", writing: "I hate this s**t. What possible excuse is there for it??? I just. Fantastic Beasts: Professor McGonagall Breaks Harry Potter Canon (sic)".

She was joined by @Meliachipics who named the situation "ridiculous". "I know JKR is bad at math but this is ridiculous. How is the biography she wrote 4 years ago about McGonagall and how she was a student under Dumbledore fits with mcgonagall being a professor in 1927?!?, (sic)" she wrote.

However, other viewers were more forgiving, with many of them advising people to wait and see the film before they cast judgement, also pointing out that it was possible McGonagall would appear in a flashforward.

Others fans online were keen to remind people that McGonagall owned a time turner, meaning that she could have easily been present at any point in time.

Twitter user @Riz27256832 reassured fellow Potterheads, putting: "Casting McGonagall in #FantasticBeasts makes sense!!! Who held the Time Turner device from Harry Potter and the Prisoner of Azkhaban before passing it to Hermione Granger... Its Professor McGonagall. Am I right @jk_rowling ? (sic)"

@DerMonarch backed up this idea, writing: "Ugh, the idiots among the Potterheads are at it again... So apparently some actress was revealed to play a "Professor McGonagall" in Crimes of Grindelwald and of course they are immediately assuming Rowling is retconning her own timeline or McG's backstory."

So, will the Harry Potter canon be broken? Watch this space.