J.K. Rowling claimed that the Harry Potter and the Deathly Hallows epilogue is today. But… it’s actually next year.

Today is September 1, which means the Hogwarts Express departs from King’s Cross Station. It’s a momentous occasion, marked by Harry Potter fans every year.

This year, however, we’re somewhat confused. Because J.K. Rowling (you know, the author of the thing) tweeted out an announcement that today is “19 Years Later” — the day described in the Deathly Hallows epilogue, when Harry and his friends sent their kids off to school:

She’s since deleted the tweet, and posted a correction blaming Cursed Child, which came out in 2016 and also takes place 19 years later (it’s easy to get it mixed up):

According to established canon, 19 years on from Deathly Hallows is September 1, 2017.

Via the Harry Potter Lexicon (and numerous other HP wikis), the Final Battle took place in 1998, and 19 years later is 2017. It even fits with the day of the week, as next year’s September 1 is a Friday (as described in the book).

Let’s be real here: J.K. Rowling just made a mistake. She’s allowed to make mistakes, just as we all should be. (If you click the below link, you’ll also see her announcing that James Potter started school last year, which fits the established timeline.)

Related: Off to Hogwarts! J.K. Rowling says Harry Potter’s first child begins school today

But it does add an interesting dimension to the discussion of canon, because the question — which we’ve had to contend with many times recently when discussing Harry Potter — is: If what the author says goes, then what happens when the author contradicts herself?

Either way: Happy Hogwarts day, everyone! Albus, Scorpius and Rose may not head off until next year, but we all get to go today.