According to a close source, "someone extended the invitation to Brad to come to Jen's party and he accepted".
An insider told People: 'They hugged and chatted for a bit, but Jen was busy making sure all of her other guests had an incredible time'.
She discussed inviting him with friends and ended up "very happy" when he attended.
Shallow Hal star Gwyneth wrote alongside a second snapshot: 'Happy birthday (last night and tomorrow) to #jenniferaniston our ray of sunshine, example of perpetual goodness.
While Aniston and Pitt had remained friendly over the years, the source said the two weren't especially close.
"They hugged and chatted for a bit, but Jen was busy making sure all of her other guests had an unbelievable time", the source added.
Would you believe us if we told you February 7, 2019 marks Jennifer Aniston's 50th birthday?
Kylie Jenner Basically Built an Entire Amusement Park for Stormi's Birthday
At the party, Kylie, Kim, Kris and Khloe were all together (with their children) to celebrate the toddler's birthday. NOT. "I had to go all out for my baby", said Jenner, who posted a photo holding Stormi in front of a neon sign.
Okay, so Brad Pitt and Jennifer Aniston are both single.
"We love you so much and you make 50 LOOK [fire emoji]", she wrote in the caption.
Jennifer's birthday party was the main event on Saturday night with a host of celebrities in attendance. "We all love you sooo!"
She said: "I don't feel a void".
The 55-year-old actor - who split from the former Friends star in 2005 after five years of marriage - was spotted making a casual entrance at the Sunset Tower Hotel, arriving alone in a black Escalade and quickly making his way inside in a bid to dodge photographers who were waiting outside.
"My marriages, they've been very successful, in personal opinion".
"Sure, there were bumps, and not every moment felt fantastic, obviously, but at the end of it, this is our one life and I would not stay in a situation out of fear". Fear of not being able to survive.
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