Newark’s high school graduation rate fell in 2018, according to the state — a surprising downturn that brings years of rising rates to an abrupt halt and defies state and national trends.

The district’s on-time graduation rate was 75.7 percent last year, a nearly 3 percentage point decline from 2017 and the first drop in five years, according to newly released state data. In June, district officials had predicted an increase, saying they expected the 2018 rate to reach an all-time high.

Newark’s disappointing outcome comes as the national graduation rate climbed to 84.6 percent in 2017, the most recent year available. In New Jersey, the four-year graduation rate reached 90.9 percent last year, Gov. Phil Murphy announced Friday. The rate represented a minor 0.4 percentage point increase over 2017 but a record high for New Jersey, which boasts one of the top graduation rates in the country.

In Newark, three struggling schools that serve many high-needs students saw the steepest declines. The on-time graduation rate plunged by nearly 12 percentage points at Weequahic High School, more than 10 points at Barringer Arts High School, and nearly 9 points at Barringer Academy of S.T.E.A.M, according to the state figures. (The two Barringer schools were combined this academic year.)

At Barringer Arts, only half of the class of 2018 graduated on time — among the lowest rates in the state, the data show.

Two selective “magnet” high schools, Science Park and Technology, saw slight dips but still had rates well above the state and district averages.

The remaining high schools made gains. Bard Early College High School, another magnet school, saw its graduation rate leap nearly 11 points to 98.3 percent. Malcolm X Shabazz High School, which like Barringer and Weequahic must accept any student who applies, boasted a nearly 7 point gain, to 68 percent.

The district-wide decrease in Newark follows years of graduation gains. Former Superintendent Christopher Cerf, who stepped down in February 2018, and U.S. Sen. Cory Booker, the presidential candidate and former Newark mayor, have touted those steady increases as evidence of the district’s progress and the success of a controversial school-system overhaul they engineered.

Last year’s graduation slump came months after Cerf left and before the current superintendent, Roger León, took over in July. An interim schools chief, A. Robert Gregory, oversaw the district during the transition.

In June, a district press release said preliminary data suggested the 2018 graduation rate would “bypass” the previous year’s, though it noted that final rates would not be available for several months. In a statement at the time, Gregory said the graduation rate and SAT scores for the class of 2018 “shatters the record for achievement in the recent history of this city and our school district.”

Gregory, who now heads the Marion P. Thomas charter school network, was not available for an interview Friday, according to an aide. Cerf did not respond on the record to a request for comment. A spokeswoman for León did not immediately provide a response.

As superintendent, León has flagged course-scheduling problems at some high schools that he said could prevent students from graduating.

In the fall, he found that about 500 seniors were missing certain credit requirements in order to earn diplomas this spring. After schools were ordered to make changes to those students’ course schedules, the number of seniors off track to graduate fell to about 140, León said at January school board meeting.

He added that school administrators would be retrained on how to ensure students are meeting graduation requirements.

“The work ahead is long,” León said.