

President Berdimuhamedow told that he cannot come because on June 29 he turns 63. "...birthdays should be celebrated with family and friends, as well as with the people of Turkmenistan." https://tass.com/defense/1169851
In 2013 when Turkmenistan's economy was relatively stable and gas prices were high, Jennifer Lopez (together w/ many other celebrities like Bulgarian-Russian pop superstar Phillip Kirkorov) came to sing for Berdymuhamedow.
For the last years, however, the celebration is much more modest. No more huge shows and international superstars. At the same time protests in- and outside of Turkmenistan put more pressure on the regime, as @gvaughan_3 writes in @Diplomat_APAC: https://thediplomat.com/2020/06/storms-spark-activism-among-turkmen-diaspora/