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Nothing awkward about it!

Brad Pitt and Courteney Cox reunited for dinner at Beso, the West Hollywood eatery owned by Eva Longoria, on Wednesday night.

Why did Jennifer Aniston's best friend and famous ex-husband (now Angelina Jolie's love) break bread together? The duo share a manager in Cynthia Pett-Dante, who was celebrating her birthday with Pitt, 47, Cox, 46 and 9 other pals, including comic actor Danny McBride.

"Brad was the first to arrive and he hung out at the bar grabbed a cocktail and sort of chatted with patrons. Nice as ever!" a witness tells Us Weekly.

Cox arrived solo a bit later, joining the gang at a table in the private room. She and Pitt "looked happy to see one another, like old friends," one observer notes. "They huddled for a good five minutes, like they were catching up."

Another witness adds, "They were very sweet to each other. He gave her a big hug."

Cox -- on a trial separatoin from husband David Arquette -- has seemingly had a bit more drama of late than Pitt, who's still happily partnered with Jolie 6 years after splitting with Aniston, 42.

"There didn't seem to be any hard feelings," said the witness of Pitt and Cox, whose close pal Aniston was infamously burned by the messy end of her marriage to Pitt. "Everyone was very relaxed."

The second witness adds that Pitt apologized for love Jolie's absence from the fete -- even showing Pett-Dante a "happy birthday" text from Jolie!

The crew feasted on tacos, flatbreads, guacamole and salad, with Pitt ordering a hearty steak and red wine. For dessert? Churros! After the meal, the group -- minus Cox, who had to go back home to daughter Coco, 6 -- hit rocker Chris Cornell's concert at L.A.'s Ford Theater.

Pitt was "incredibly nice," the second Beso witness gushes. "Super super nice guy!"