“Some days are grumpier than others,” the Instagram caption read.

It appeared next to a photo of the Internet’s most famous and beloved cat, the one with the perpetually miserable mug.

But this was no ordinary post Friday morning on @realgrumpycat, the wildly popular Instagram account with more than 2.4 million followers, who have grown to adore the cat’s perma-scowl.

Grumpy Cat’s owners had come to share some extremely :( news:

Grumpy Cat is dead.

The “grumpy” cat, whose real name was Tardar Sauce, died on Tuesday of complications from a urinary tract infection.

She was 7.

“Besides being our baby and a cherished member of the family, Grumpy Cat has helped millions of people smile around the world — even when times were tough,” her owners said. “Her spirit will continue to live on through her fans everywhere.”

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‪#MayTheFourth be awful. Always. ‬

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Grumpy Cat wasn’t, in fact, perpetually grumpy; her distinctive scowl was caused by a form of dwarfism.

She first achieved some level of Internet celebrity in 2012, after pictures featuring her frowning face went viral on social media, then turned into a mean-mugging meme. Within 24 hours, a Reddit post that included images of the cat was trending with more than 25,000 upvotes, according to Know Your Meme, a website that tracks viral Internet content.

It wasn’t long before Grumpy Cat was everywhere. She appeared on TV, popping up in episodes of “American Idol,” “The Bachelorette” and WWE’s “Monday Night Raw.”

In 2013, the feline beat out “Gangnam Style” and the “Harlem Shake” to win Meme of the Year at the Webby Awards. The following year, she scored her own Lifetime holiday movie, “Grumpy Cat’s Worst Christmas Ever,” a two-hour spectacle featuring the voice talents of actress Aubrey Plaza as the title character.

Two years later, she made her Broadway debut, a one-night only appearance in Andrew Lloyd Webber’s musical, “Cats.” Of course she did.

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#GrumpyTakesBroadway #CatsBroadway

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In 2016, her sculpture was added to Madame Tussauds Las Vegas — and the cat was invited to curl up alongside her own wax figure.

She also crashed the world’s most famous grumpy-cat comic franchise, crossing over into the world of “Garfield.” On Friday, “Garfield” paid tribute to Grumpy Cat.

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RIP Grumpy Cat. @realgrumpycat

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By the time of her death this week, Grumpy Cat had amassed nearly 4 million combined followers on Instagram and Twitter, with a Facebook page that boasts 8.5 million likes.

Grumpy Cat also became something of a cottage industry.

As The Post’s Travis M. Andrews reported, the cat’s owner, Tabatha Bundesen of Morristown, Ariz., saw in her mixed-breed cat “a cash cow and a lifeline. The cat’s unexpected fame allowed Bundesen to quit her job waitressing at Red Lobster,” Andrews wrote, adding “Bundesen later formed Grumpy Cat Limited, monetizing her cat.”

In its first few years, the company, which rolled out a line of branded products, reportedly raked in anywhere from $1 million to $100 million, Andrews reported. The feline also added “spokescat” for Friskies to her résumé in 2013, according to CNN.

Go to the Grumpycats.com shop today and you’ll find hundreds of products available for purchase, from ugly Christmas sweaters and laptop sleeves to drink coasters and guitar straps — all of them, of course, bearing the cat’s famous frown, usually along with a similarly surly message.

Following Friday’s somber announcement, social media was filled with tributes to the famous feline, offering condolences to Tardar Sauce’s family and — in the true spirit of Grumpy Cat — meme-ing her in death.

Her death announcement noted that Grumpy Cat “passed away peacefully . . . in the arms of her mommy, Tabatha.”

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Some days are grumpier than others...

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Garfield creator Jim Davis meets Grumpy Cat

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To hate or not to hate...

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