Caitlyn Jenner in Austria for Life Ball While Brody Preps for Wedding Without Her

Caitlyn Jenner won't be attending her son's weekend wedding ... because she's more than 7,000 miles away from Bali preparing for another big event.

Caitlyn touched down in Vienna, Austria Friday, where she'll be attending Life Ball 2018 ... a benefit raising money for amfAR's research to find a cure for HIV/AIDS.

We broke the story ... Brody Jenner's deeply hurt his dad is taking a pass on going to his wedding in Bali Saturday, which our Brody sources say was due to Caitlyn having a lucrative business opportunity she couldn't pass up.

It's unlikely the "lucrative deal" was the Life Ball, but it seems pretty certain she won't be surprising Brody last minute by showing up to see him say "I Do."