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), which is said to be scheduled for Thursday, 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.
55 hours married
Spears ("Baby One More Time") and fitness trainer Asghari have been engaged since September 2021.
There was initially no official confirmation of the wedding date on Thursday from the singer's spokesperson.
It would be Spears' third wedding.
The singer was married to childhood friend Jason Alexander in 2004, but only for 55 hours.
The marriage was annulled.
In 2004 she married her dancer Kevin Federline.
With him she has two sons, Sean Preston (16) and Jayden James (15).
The couple separated in 2007.