Prince Louis, William and Kate’s youngest son, turns six-years-old

LONDON (NBC, KYMA/KECY) - A photo of Prince Louis, taken by the Princess of Wales, has been released to mark the young British royal's sixth birthday.

"Happy 6th birthday, Prince Louis!" the pair captioned the photo in a post on X, adding the cake emoji. "Thank you for all the kind wishes today." The post gave the photo credit to Kate Middleton.

The photo is the first personal post the account has posted since she shared in March that she's undergoing treatment for cancer.

Prince William and Kate traditionally release new photos every year, many times taken by Kate, in honor of each of their kids' birthdays.

The photo of Louis comes after Kensington Palace became embroiled in controversy surrounding a family portrait released on March 10, or Mother's Day in the U.K. as the photo of Kate, George, Charlotte and Louis was later deemed not to be used by multiple photo agencies after it was determined it had apparently been "manipulated."

The day after the photo was posted, Kensington Palace released an apology from Kate.