More than 100 licensed cannabis dispensaries in New York were allowed to open too close to schools and may have to move, state regulators said on Monday.

State law prohibits dispensaries from opening within 500 feet of schools. For the past three years, regulators in the Office of Cannabis Management have measured the distance from the entrance of the potential dispensary to the entrance of a school. However, the agency said on Monday that the distance should have been measured to a school’s property line.

The announcement has created uncertainty around the future of dozens of dispensaries at a time when suitable locations have become increasingly rare and expensive. A vast majority of the affected businesses are in New York City and owned by veterans, people affected by the state’s past anti-marijuana laws and others who were given preference to receive licenses.

Felicia Reid, the agency’s acting executive director, told her staff in an email obtained by The New York Times that the affected businesses include 60 dispensaries that are currently open and 45 others that are getting off the ground, as well as 47 applicants who were required to secure deeds or leases in advance. Officials said the change stemmed from a review of the agency’s practices that Ms. Reid ordered last year.

In letters to the businesses, Ms. Reid acknowledged that her agency’s decision might have harmful repercussions for people who have poured their time, money and energy into jump-starting the legal cannabis industry.

“To give you this news, and for the weight of it, I am incredibly sorry,” she said.

In a statement, the agency said it was seeking an unspecified legislative solution to help the dispensaries stay in place. But in online guidance, officials cautioned that if lawmakers did not act, the agency could not renew the dispensaries’ licenses at their existing locations. The agency has also set aside $15 million to help cover the expenses of finding a new location for the affected applicants looking to open dispensaries.

Damian Fagon, the agency’s former chief equity officer in charge of helping business owners from underrepresented groups join the cannabis industry, criticized the reassessment of the proximity rules and said that it showed disregard for the social justice aims of the law legalizing recreational cannabis in New York.

“After wasting $50 million in public funds on a private equity debt trap, a politically motivated rule reversal is now diverting another $15 million from the very communities the law was written to help repair,” he said.

The agency said the change was not discretionary but a matter of following the law.

Joe Rossi, a lobbyist for the cannabis industry, said that the agency was correcting the mistakes of its previous leaders, who had misjudged their authority to interpret the law.

“This is a calling for course correction” by state lawmakers, he said, adding, “And the way for there to be the most minimal damage possible is for them to grandfather them in.”

In December 2023, Deniz Ozkurt opened Hush, a dispensary in the Bronx, after months of delay caused by a legal injunction. His license is up for renewal this December. He said that the cannabis agency hadn’t given him any guidance on whether he should keep ordering products or what to tell his 15 employees, but the idea of uprooting his business infuriates him.

“I’m fighting this tooth and nail,” he said. “We have an established business and we’ve been there for two years.”