Why Kourtney Kardashian Was MIA from Sister Kim Kardashian's Big Birthday Bash

Kim took to Instagram to share pictures of the birthday celebration and to thank her family and friends for attending the big celebration -- before acknowledging her sister's absence.

"So blessed to have hit the jackpot of friends! I couldn't have ever dreamed I would be so lucky to call these girls my friends ✨," captioned The Kardashians star. "Thank you for all the birthday love ❤️ and Kourt, I'm jumping in bed with you next week for our bed rest picnic."

Despite missing the party, Kourt still took to Instagram to share a tribute to her sister on the special day.

"Happy happy birthday to my first sister," she wrote on her Instagram stories. "Thank you for all those years of bossing you around and you actually listening to all of my crazy ideas."

"People think the fights they've seen on TV are bad," she added. "If only they got to witness the hair-pulling, nail-digging ones from early high school, The joys of sisterhood."

Kourtney's sweet birthday tribute for Kim comes after the two got into a now-infamous nasty fight over Kim's collaboration with Dolce & Gabbana, which went down on the last season of The Kardashians and spread into the current season.

ICYMI: Kourtney made it clear previously she felt Kim's collaboration with Dolce & Gabbana stepped on the toes of her recent wedding celebrations, during which she wore curated looks from the brand's vault. She also believed the partnership spoke to a larger issue she had with Kim, who she felt didn't prioritize family over business deals.

While the pair seemed to hash things out last season, Season 4's premiere kicked off with them already at odds with one another again. This time, the tension came after they began watching the Season 3 episodes as they dropped -- seeing the nasty comments they each made about other behind their backs during confessionals or conversations with other family members amid their feud.

That led to an explosive phone call between Kim and Kourtney, with the latter calling the former "a f--king witch" who she hated.

Fortunately, it appears that their relationship is on the mend.

During a recent episode of The Kardashians, Kim explained that things are on the upswing while on a trip to Milan for a Dolce & Gabbana engagement. During the getaway, Kim said that she began getting some sweet text messages from Kourtney -- despite their past drama involving the same designer.

"I feel like it's a step in the right direction in moving past it, moving past all the drama, I want her here," Kim explained in a confessional, before Kourtney opened up about the situation in her own.

"I think we both said things that we're not proud of. But anyone who has sisters or siblings, knows the dynamic," said Kourt. "You can get into a crazy fight and then you can each other a funny text and everything's all good."