Legendary showbiz haunt the Friars Club is going up for sale amid a major debt crisis, Page Six has learned.

The 125-year-old private members club — which has counted Frank Sinatra, Joan Rivers and Jimmy Fallon among its members, alongside an endless parade of showbiz stars and operators — has had its home in a stunning 55th Street mansion since 1957.

But the club has suffered from an aging membership and dwindling dues for years, and we’re told that the COVID-19 crisis forced it to borrow around $13 million to keep the place afloat.

Now we’re told that it can’t keep up with the monthly payments on the loan, and the lender is coming after the club for the cash.

So the board has decided to sell the building in an attempt to keep the club up and running.

We’re told there’s a likely buyer who is prepared to cough up $18 million to buy the building, and lease it back to the club.

Lawyer Arthur Aidala, who’s running the Friars, tells us there are several offers — some from buyers who simply want to act as a landlord and collect rent from the club, and some who want a hand in revamping the club.

He wouldn’t name the current high bidder, but said it’s a company fronted by a well-known individual. He also said they’d be happy to entertain offers from companies behind fashionable private clubs, such as Soho House or Casa Cipriani.

“We’re not looking to throw tradition out the window,” he told Page Six. “But at the same time, it has to appeal to everyone, not just a certain age group.”

“We have to remember it’s 2023, not 1923,” he added.

Gristedes and WABC radio owner, and former mayoral candidate, John Catsimatidis, tells us he has made an unofficial offer to the board — although it seems unlikely his $6 million bid will be successful.

Aidala tells us the board isn’t entertaining offers from potential buyers that don’t want to continue to use the building as the Friars’ clubhouse. “We could easily sell to someone who wants to turn it back into a townhouse,” he told us. “But nobody wants that to happen.”

He also said City Hall is unofficially, but actively, involved in the sale, because it’s such a significant New York institution. “Nobody is rooting for this place to go down,” he said.

Before COVID hit, the club closed down for repairs because of an alleged flood in the basement.

Then, during the lockdown, it underwent major renovations and was preparing to reopen with a restaurant run by famed hospitality mogul Charlie Palmer on the first floor.

It briefly opened its doors in 2021, promising a fresh new look to the club, which costs up to $5,000-a-year in dues. But it closed again for more renovations to ready the kitchen for the new dining spot.

But we’re told that the board decided in January to lock the doors and furlough the staff for six months while it tried to get the club on a solid financial footing.

As of now, the Palmer restaurant is on hold, we’re told.

As Page Six has reported, the club has been through the legal wringer of late.

In 2017, it was raided by the FBI as part of what appears to have been an investigation into the club’s then executive director Michael Guyre, who pleaded guilty in 2019 to failing to pay taxes on some $433,000 in “personal expenses and other benefits provided to [the] executive director by the club.”

He left the club in 2020. The club itself wasn’t accused of wrongdoing.