Backup quarterback Derek Anderson called Hangartner one of the most popular players in the locker room, saying, "It's tough, but somebody is going to have to step up."
Hangartner was due to make $1.575 million this year.
Left tackle Jordan Gross, who has played six seasons with Hangartner, said he was surprised and saddened by the move.
"He got a text to go see coach Rivera first thing in the morning, and that's never good news," Gross said. "Honestly, I was wondering if he was going to get traded to Denver, because everyone knows they have a (injury) situation there. But yes, it surprised me."
Teammates often referred to Hangartner by his nickname, "Piggy."
Gross said the move is a solemn reminder that the NFL is a business.
"You hope that management knows what they're doing and that it is for the better and it will make us a better team," Gross said. "That's really what we have to focus on."
NOTES: Gross, the team's 33-year old, two-time Pro Bowl tackle, said Thursday he doesn't want to play for any other team except the Panthers, but said he isn't thinking about retirement. His contract was restructured this offseason in a manner that the Panthers will almost certainly have to release him after this season. But Gross reiterated he wouldn't rule out coming back to play next season for Carolina under a different contract "if they want me back."