Democratic Mayoral candidate Muriel Bowser is congratulated by Ward 5 Council member Kenyan McDuffie in Washington on April 01, 2014. (Marvin Joseph/The Washington Post)

Top D.C. election officials said Thursday they have fixed problems with computer switches and servers that caused a four-hour delay in reporting results of the city’s April 1 primary. But in sometimes contentious testimony before a D.C. Council committee , the city’s elections chief said he cannot ensure a smooth night on Nov. 4.

“While we have resolved the technical issues . . . I cannot guarantee” there won’t be “more glitches,” said Clifford D. Tatum, executive director of the D.C. Board of Elections.

Tatum also refused to make any promises about what time the vote tallying would be finished after the close of polls in the city’s general election. “We will plan for every reasonable contingency,” Tatum said, “but we cannot make any guarantees to when the election night process will be complete.”

Tatum said that on Nov. 4 the board would have 45 “roving technicians” to deal with any issues that arise at polling places.

Despite record-low turnout on April 1, a vote-counting delay made it impossible to call the mayor’s race and other key contests until after 10 p.m., nearly four hours after polls closed.

At the heart of the delay, officials said then, were five electronic voting machines from which results were not properly extracted. Officials said they had to fan out across the city to check the machines and retrieve accurate counts.

A month later, however, election officials offered a new explanation: The issue was not five mishandled electronic voting machines, but a broad computer network failure. The network failure was a mystery to elections officials even as it unfolded, Tatum said at the time.

The long wait — unusually long even by the generous standards of the Board of Elections — led to criticism from candidates and their supporters, left standing around for hours waiting to hear the results of a closely watched mayoral race, among other contests.

The glitches contributed to a tense and halting series of statements by Democratic mayoral candidates Muriel Bowser and Vincent C. Gray. Bowser’s campaign proclaimed victory almost as Gray’s campaign said it was still waiting for missing votes. With their victory and concession speeches jumbled, Gray never called Bowser to concede.

Council member Kenyan R. McDuffie (D-Ward 5), chairman of the Government Operations Committee, criticized answers by Tatum on Thursday as vague. He questioned why the board still had not delivered a promised post-mortem on the election within an expected 90 days.

McDuffie said Wednesday that he had expected a report in July detailing the election board’s problems in April. He said he had tried twice to get it but had been told it was not ready.

On Thursday, Deborah Nichols, who chairs the election board, said that she had not seen such a report and that, if there was one, it wouldn’t provide any more information than the board had received during a hearing before McDuffie’s committee five months ago.

Tatum said there was a report, but he had decided to revise it after the board’s “success” at holding an election for a school board seat in July. Nichols said she would make sure the report reached McDuffie by early October.

Nichols repeated her contention Thursday that to fix the board’s elections operations would require millions of dollars for new electronic voting machines and server upgrades — and perhaps an additional $2 million in computers and other office improvements.

At one point in the hearing, Nichols suggested that McDuffie was blowing the April election night delays out of proportion.

She singled out a failure that the election board had conceded in April — not delivering pencils to voting places — and said McDuffie seemed intent on turning the pencils into “some grand failure” of the board. She added that perhaps McDuffie and the council should “replace us all.”

McDuffie fired back at the pencil explanation, calling it “disingenuous.”

“This is not an attempt to blow it out of proportion,” McDuffie said. “This is an attempt to make sure the election is conducted competently.”