Kanye West and his former best friend Jay Z haven't seen or spoken to each other in years. Both men attended Diddy's star studded 50th birthday party last night, and spoke to each other.

The two were close friends, and went on tour together back in 2015 - with their Watch The Thrones album. But while on tour, their relationship quickly soured.

According to Jay Z's people, Jigga lent Kanye West millions of dollars, and was never paid back.

But Kanye's folks say something different - they allege that Jay Z somehow swindled them out of tour and streaming money.

Diddy's 50th birthday bash went down Saturday at his $40 million Holmby Hills home, where Diddy celebrated with Beyonce, Kim Kardashian, Khloe Kardashian, Kylie Jenner, Dr. Dre, Pharrell Williams, Cardi B, Offset, Chadwick Boseman, Post Malone, Tyler Perry, Kobe Bryant, Machine Gun Kelly and on and on.

Well whatever their beef, the two moguls put it aside - and stood by each other last night at Diddy's 50th birthday party. 

There was definitely some awkwardness between them though. Look:

Here are some video and pics from the event:

According to TMZ, Diddy's birthday is actually November 4, but he apparently waited so all his friends could join him.

He's had a rough patch for sure ... a little more than a year ago the mother of his twins -- Kim Porter -- died due to complications from pneumonia.

The cake inscription was short, sweet, and to the point. It simply said "LOVE."

A good time ... clearly had by all.