San Franciscans have been eagerly awaiting the expansion of a wildly popular bakery — but the owner announced Wednesday that those plans have been crushed by the city’s bizarre permitting rules.

Sophie Smith, who owns Butter & Crumble, said on social media she was “so disappointed” to share the news that her dream of opening up a second location at 301 Union Street is now canceled.

“I am heartbroken to announce that an unexpected roadblock has forced me to walk away from that space,” she said. “It was crushing to share this news with my employees, who were planning the next steps of their careers at The Cake Shop.”

Since opening its first brick-and-mortar shop in 2023, Butter & Crumble has won fans for its mouthwatering pastries, cakes and “cruffins” — a mash-up of muffins and croissants that can attract long lines at its current location near Fisherman’s Wharf.

In February, the business announced plans for a second location focused on cakes.

Smith said she spent a year and countless hours planning for the shop, along with tens of thousands of dollars on architects, preliminary construction investigations and vintage plate ware. She trained team members for new management roles at the 1800-square foot commercial space.

Legislation by city Supervisor Danny Sauter was intended to help pave the way for the location to become a cake shop, and Smith signed the lease in February.

But a problem emerged: the space was actually two different lots owned by the same landlord.

“The problems this creates are potentially massive, as you cannot just join two buildings for a commercial use like mine,” she said, “without new rollup doors, two separate evacuation routes and new fire sprinklers on both sides of the building, not to mention zoning issues.”

She said she was assured by the landlord and a city department that because the two-lot location had long been used as one space, she could plow forward. So she did.

However, in July, the city Department of Building Inspection discovered that a previous permit on that site showed a wall separating the two lots with no record of it being removed. That error threw the whole project into peril.

“There was a wall removed at some point when it probably shouldn’t have been,” Sauter told the San Francisco Chronicle, and that raised safety concerns.

“It’s such a unique set of circumstances and also quite unique to that space,” he added. “At the end of the day, it’s really sad.”

Smith’s attempts to open up a new shop come as San Francisco Mayor Daniel Lurie has pushed to revitalize the city. He had worked to streamline the city’s permitting process and make changes to how city departments coordinate.

San Francisco’s Office of Small Business told the Chronicle in a statement that it’s “sorry for the setback Sophie and the team experienced with this space,” and it “will continue to support them as they navigate their next steps.”

The Post reached out to the building inspection department for comment.

Now, Smith said she’s refocusing her attention on her existing location, but she hasn’t given up on a second location.

“The Cake Shop became such a real tangible dream for me…and I know it’s not lost,” she said. “I know we will make this happen.”