The American Jason Alexander (40), who was briefly married to Britney Spears in 2004, was arrested on Thursday (local time) in front of the pop singer's house in California.
This was confirmed by the police in the Ventura County district at the request of the German Press Agency.
The police received a call that a man had entered the singer's property without permission.
Alexander was held in custody on an outstanding warrant on a separate matter, Sheriff Jason Karol said.
Alexander is said to have tried to disrupt the preparations for the wedding of Spears (40) and her fiancé Sam Ashgari (28), US media reported.
The celebrity portal "TMZ.com" posted a video that Alexander is said to have published as a live stream on Instagram.
It shows him walking through the property's house and garden, telling staff that Britney invited him.
He was here to "storm" the wedding.
Preparations for a celebration are apparently underway on the site, and a large tent has been set up.
Despite the disruption from her ex-husband, Spears and Ashgari tied the knot on Thursday evening (local time).
The wedding ceremony took place on Thursday evening (local time) at the pop star's estate in Thousand Oaks, California.
"I am absolutely thrilled that the day has come and that they are married," said Asghari's spokesman Brandon Cohen after the ceremony of the German Press Agency.
"I know that he (Asghari) has wanted this for a long time." According to media reports, the wedding ceremony took place in front of around 60 guests.
According to People.com, singer Madonna, actress Drew Barrymore, reality star Paris Hilton and fashion designer Donatella Versace were invited.
Eonline.com posted numerous photos of the arrival of the celebrity wedding guests.
Spears ("Baby One More Time") and fitness trainer and model Asghari met on the set of their 2016 music video "Slumber Party," in which he played her lover.
They have been engaged to each other since September 2021.
It is the third wedding for the singer.
Spears was married to childhood friend Jason Alexander in 2004, but only for 55 hours.
The marriage was annulled.
A few months later she married dancer Kevin Federline.
With him she has two sons, Sean Preston (16) and Jayden James (15).
The couple separated in 2007.