Nibbler’s Restaurant, the diner in Beverly Hills known for its flannel cakes and tuna melts and a Westside institution for 45 years, has closed its doors and filed for Chapter 7 bankruptcy.

The Nov. 1 filing comes after several years of declining business as the restaurant’s customer base aged and potential younger customers flocked to trendier restaurants on nearby Restaurant Row and in West Hollywood.

It also comes amid a dispute between current and former owners, according to bankruptcy attorney Robert Scott. Current owners Shahab Fatemian and Amir Razmara bought the restaurant from Javid Mansouri last December with hopes of reviving its fortunes, he said.

“The current owners saw that the restaurant wasn’t making money,” he said. “They realized they would have had to put in at least $250,000 to turn it around. Given the current environment, the principals felt they did not want to throw good money after bad money.”

Scott said the restaurant has been closed since Oct. 30. Signs on the door say it is “closed temporarily for renovations.” Scott said the company’s assets and liabilities were still being tallied.

The owners themselves could not be reached for comment. But Scott said they believed the restaurant would “reopen within 60 to 90 days.”

Nibbler’s was founded in 1956. In the late 1960s, it moved to its current location where it prospered for several years as a ’50s-style diner. It became popular with middle-aged customers who grew up with such diners.

By the 1980s, the customer base became older. “They did have an aging, loyal clientele. By its very nature, such a clientele tends to diminish over time,” said Janet Lowder, president of Restaurant Management Services.

In the mid-1990s, the original family owners sold the restaurant to Mansouri.