The National Children’s Museum, the once-beloved institution that has been closed for four years, has delayed the reopening of its new Pennsylvania Avenue space.

The museum was scheduled to open to the public Nov. 3 in the Ronald Reagan Building, following two special events Nov. 1 and 2.

A new opening date has not been determined.

The museum has canceled its ribbon-cutting ceremony, but will host a gala celebration Nov. 1 and a family day Nov. 2 from 1 to 4 p.m., board member Rob Volmer said. About 500 people are expected at the gala, which will feature cocktails and dinner at the Mellon Auditorium followed by dessert in the museum. The sold-out family day event is expected to draw about 1,000 people.

“All the exhibits are ready to go,” Volmer said. The opening events can occur without the certificate of occupancy, which is a green light from the D.C. government confirming that construction is complete and that the space is ready for public use.

“There’s a checklist of things that need to be in place,” Volmer said, declining to be more specific.

Some of the delay was caused by unforeseen problems in the federally owned building that had to be fixed, according to a museum official, and the additional work was slow to be approved by federal officials.

The delay is another setback for the long-shuttered museum. Originally called the Capital Children’s Museum, it welcomed generations of visitors to its H Street NE location, a former convent, from 1974 to 2003. The museum sold that property in 2004 and planned to reopen in a new space, designed by architect César Pelli, at L’Enfant Plaza. That project, and a second one also by Pelli, never happened.

As its leaders considered its future, the museum operated in temporary spaces at National Harbor from 2009 until 2015.

In 2017, museum officials unveiled its new site at 1300 Pennsylvania Ave. NW, a few blocks from the Mall and near parking and the Federal Triangle Metro stop. The $15 million project — a hybrid science and children’s museum in 30,000 square feet — was supposed to open in spring 2019.

A highlight of the space will be its Dream Machine, a 50-foot climbing structure featuring netting, ropes and slides at the entrance off the Pennsylvania Avenue plaza.