It appears the two sides couldn't come to an agreement when it came to term during contract negotiations. As Lindgren was seeking a longer deal, at a $5 M cap hit, while the team wanted a shorter term at two to three years for $4.5 M.
While the team and Lindgren couldn't come to terms, when it came to the length of the deal, it does give both the defenseman and team time, to revisit the deal on January 1st.
Lindgren has been a key defenseman for the Rangers, with this last season the defenseman posting 17 points(3 G, 14 A) in 76 games, averaging 19:21 minutes on ice.
For now, the long-term extension is off the table but the Rangers get a warrior defenseman back in the ranks, and Lindgren gets the chance to prove he deserves it.