It seems Daryl Hall and John Oates have "Lost That Lovin' Feeling."
The former musical partners appear to be in the midst of some kind of litigious battle, but details on what prompted the discord are under tight wraps.
What is known is that Hall filed a lawsuit against his former bandmate Oates in Nashville's chancery court on Nov. 16 alongside a motion for a temporary restraining order, which the court granted the following day with an effective date of Nov. 30.
The court documents are under seal, but court records show the case is a contract or debt lawsuit. Details on the reason for the restraining order, however, are scant, though it could be used alongside this type of dispute to keep economic interests separate.
The two musicians are known for their namesake pop-rock duo Daryl Hall & John Oates, though they're commonly known as Hall & Oates.
Both of the Philadelphia-bred men were heading their own musical group when they met 1967, but two years later they formed their now iconic musical pairing, in which Hall is typically lead vocalist and Oates is lead guitar and backing vocalist.
In 1972, they released their debut studio album "Whole Oats" after signing with Atlantic Records, and the rest is rock 'n' roll history.
The duo went on to have a nearly five-decade-spanning career, complete with seven RIAA-certified platinum albums and six more gold. Twenty-nine of their 33 singles between 1974 and 1991 reached the top 40 of Billboard's Hot 100, including six No. 1 singles: "Rich Girl," Kiss on My List," "Private Eyes," "I Can't Go for That (No Can Do)," "Maneater" and "Out of Touch."
Beyond their success in the '70s and '80s, Daryl Hall & John Oates still remain the most successful duo of all time.
They were inducted into the Songwriters Hall of Fame in 2003 and the Rock and Roll Hall of Fame in 2014. They also ranked 18 in Billboard's Hot 100 artists of all time list.
But the path to their milestones hasn't been without bumps on the road.
For decades, the pair have both pursued solo work, along with separate tours. And last year, Hall told the Los Angeles Times he had no plans to work with Oates anytime soon, saying, "Time will tell," and expressing his annoyance at the two always being compared to each other.
Also last year, Hall shared on Bill Maher's "Club Random" podcast how he really feels about the musical partnership between himself and Oates.
"You think John Oates is my partner? He's my business partner. He's not my creative partner," he said to Maher. "John and I are brothers, but we are not creative brothers. We are business partners. We made records called Hall & Oates together, but we've always been very separate, and that's a really important thing for me."