Britney Spears' Ex-Husband Jason Alexander's Warrant for Alleged Bracelet Theft

Britney Spears' first husband Jason Alexander not only sucks at wedding crashing ... he's also a horrible houseguest, who allegedly swiped jewelry from a woman who let him rent a room.

Jason's antics at Britney's wedding have him in a world of legal trouble beyond the trespassing and battery -- we've learned he already had a felony arrest warrant in Napa County where cops say he made off with a $2,000 bracelet.

The Napa County Sheriff's Office tells TMZ ... Jason is charged with 2 felonies there, including grand theft, related to the 2015 incident.

According to law enforcement ... Jason had only been living in the woman's house for about a month when she says she noticed jewelry missing from her bedroom. She claims Jason initially denied stealing a bracelet, but police say Jason later admitted to the woman he stole the bling -- a diamond and sapphire tennis bracelet valued at $2k -- and sold it to a local pawn shop.

Cops say the woman called police in Feb. 2016 and the investigation led them to a pawn shop where they discovered Jason had sold the bracelet for only $180.

Police say they were able to get the jewelry back to the woman, and a felony warrant was issued for Jason's arrest.

As we first reported ... Jason went live on social media Thursday as he tried crashing Britney's wedding to Sam Asghari at her home in Ventura County, and he ended up in jail.

Cops say Jason was armed with a knife when he was on Britney's property ... and now there's an emergency protective order stating Jason must stay at least 100 yards away from the newlyweds, Britney and Sam.

Jason, who was married to Britney for only 55 hours following a spur-of-the-moment ceremony in Las Vegas back in 2004, was booked for trespassing, vandalism and 2 batteries ... related to altercations with Britney's security team.