With Boston’s schools opening in just 19 days, top officials pledged a smooth start Thursday despite a computer problem with department wait lists that left thousands of families unsure of their chances of getting into a preferred school.

“I am fully confident we are going to be ready to go day one,” Superintendent Tommy Chang told reporters on the City Hall steps.

Parents of children wait-listed for their favored schools were not able to view their child’s rank on the lists until Thursday, when they became available online, according to the department.

Currently, 8,140 students are on wait lists, but 6,223 of those students have been assigned to a school — just not to their top pick.


Of the 1,917 students still unassigned, almost 97 percent applied for prekindergarten seats, which are not guaranteed and are not required by state law. Only 59 applicants for kindergarten seats — which are required by law — are still awaiting their school assignments.

“What this really tells us is there is a great demand for pre-K seats here in Boston,” said Chang, who took office July 1. “And we cannot fulfill that need because we don’t have the space and we don’t have the funding.”

Chang said he and Mayor Martin J. Walsh are committed to expanding prekindergarten options over time to serve every interested family.

The wait lists were delayed by “technical challenges” related to the Aspen Student Information System software being used for school assignments for the first time this year, schools officials said. The issue was first reported Thursday in the Boston Herald.

In the spring, some families received their school assignments late, with the department pointing to problems with a computer algorithm used to make the assignments.

Officials had hoped to notify families of their wait-list positions in June, after the last of three rounds of registration, said Kim Rice, assistant superintendent of operations.


But the software struggled with the complex priorities of the new school assignment system introduced last year, Rice said.

To ensure that its rules were properly applied, workers carefully reviewed student assignments.

“Until we were sure that they were absolutely perfect, we didn’t feel comfortable releasing them,” she said.

Kristin Johnson, a member of Boston’s Citywide Parent Council, said the delay has frustrated many parents of prekindergarten applicants.

“This is the first entry point these parents have into BPS, and it’s been a terrible disaster,” Johnson said. “BPS really has to get the lottery under control or these families will just leave.”

Despite the technical issues, Chang said, other critical elements of the school start are in order.

Bus routes have been set and sent to parents, he said — a contrast to last fall, when buses showed up late or not at all. And Madison Park Technical Vocational High School students have their class schedules in hand, unlike last year, when some students waited days for schedules.

“Madison Park was the first school to have their schedules loaded into the system,” Chang said.

Johnson was skeptical that the year would start smoothly.

“There are a lot of unknowns,” she said. “A lot of schools are changing to extended learning time . . . and there’s been no communication from BPS to incoming parents this summer.”

Jeremy C. Fox can be reached at jeremy.fox@globe.com.