The upcoming Harry Potter TV series will be a new adaptation of the books, but it should ignore certain canon changes made by J.K. Rowling in recent years. While details are still unclear, the HBO Max show is expected to follow the plot of the books, similar to the film series. This remake presents an opportunity to correct any mistakes made in the Harry Potter movies and include missed details from the original books.
The Wizarding World, also known as the Potterverse, has expanded beyond its original seven novels and eight films. Fantastic Beasts and Where To Find Them, originally a fictional guide in the books, became a trilogy of films. The play Harry Potter and the Cursed Child, set 15 years after the events of Harry Potter and the Deathly Hallows: Part 2, also added to the story. However, J.K. Rowling has made some strange canon alterations over the years that should be disregarded in the new series.
One such alteration is J.K. Rowling's revelation that Harry's Uncle Vernon would have voted leave in the UK Brexit referendum. While this topic won't come up in the new series as it is set in the 1990s, there is no need to suddenly make Mr. Dursley more vocal about his political opinions.
Another change is the explanation that Nagini, Voldemort's pet snake, was once a human woman. This creates more plot holes than it fixes and should be ignored in the new series.
The introduction of Delphini, Voldemort and Bellatrix's daughter, in Harry Potter and the Cursed Child also creates inconsistencies. The series would have to address how Bellatrix could give birth and still be involved in the events of Dobby's death. This concept seems farfetched and should be explored carefully.
Rowling's reveal in 2015 that Hogwarts came with no costs contradicts previous scenes in the books and films. Characters like Harry and the Weasley family were shown managing their finances, indicating that magical education required expenses. This retcon raises plot holes that need to be addressed in the new series.
A lesser-known retcon is the fact that Wizardkind didn't use Muggle plumbing until the 18th century. This seems unnecessary to include in the series, considering the significance of bathrooms in the story.