Lily Allen just made the Christmas shopping mistake of every parent's nightmare.

It was two days before Christmas when singer Lily Allen realised she’d made the mistake every parent fears come Christmas time.

The presents she’d ordered online for her two daughters – six-year-old Ethel and Marnie, four – would not be arriving in time for Santa to place them under the tree.

They would not be there for the girls to excitedly (and as most parents know, loudly) open on Christmas morning.

It wasn’t because the shops were out of stock. It wasn’t because an influx of people sending mail had caused a delay in the postal service.

Nope. The 32-year-old singer had failed to realise her credit card had expired, meaning she never actually completed her online purchases.

LISTEN: Run out of magical ideas for Elf on the Shelf? Holly Wainwright has a good one, and all you need is an egg, glitter and a Kinder Surprise.

Sharing the dilemma on Twitter, the Smile singer said she only noticed her error when she logged online to check the shipping details of the items, and found an email asking her to review her payment details.

“F*CK. When your card expires and you don’t check your emails,” she Tweeted, alongside a snap of the items that needed “payment revision”.

Poor Ethel and Marnie will have to wait until after Christmas to receive the four different sets of Barbie dolls their mum had meant to order.

The singer's fans were quick to offer words of wisdom and advice, with many reminding her that there was always a way to keep her kids happy come Christmas morning.

"Oh no!!! I am sure you will be able to work everything out in time!" one mother wrote.

"You could always say Santa dropped off presents he forgot if that's still an option! Good luck!"

Others said they didn't envy her for the fact she would now have to brave the Christmas crowds at the shops to purchase some last-minute, replacement gifts.

"Nightmare. I don't envy you having to shop this late," one user wrote.

Lily Allen isn't the only celeb to have a little bit of a 'Christmas fail' in 2017: yesterday, singer Pink shared a note her six-year-old daughter had written to Santa, after noticing her Elf on the Shelf hadn't moved in three days.

Translation: MOM FAIL “santa, I am worried about Chippy, he has been in the same spot for 3 days. I don’t know why.” #elfonthesamedamnshelf

A post shared by P!NK (@pink) on Dec 22, 2017 at 4:16pm PST

"Santa, I am worried about Chippy, he has been in the same spot for three days. I don't know why," Willow wrote in her note to Santa.

"Translation: MOM FAIL," Pink captioned the image on Instagram.

Ah, celebrities, they're just like us... especially during the craziness of the Christmas season.

LISTEN to the latest episode of Mamamia's parenting podcast, This Glorious Mess: