Primary Day was a total snoozefest for one Upper West Side poll worker — whose on-the-clock napping was just one of countless snafus to frustrate city voters.

Tyron Brewington, who was paid $200 to man a ballot-marking device for disabled people, instead was slumped over in his chair catching Zs during the gig.

His fellow polling-station workers at PS 75 on West End Avenue were hardly amused by the Rip Van Winkle routine, saying they’d made numerous complaints to the city’s Board of Elections.

“He’s been here before and he’s gotten worse,” one volunteer said.

Another worker echoed the remarks Tuesday: “This gentleman has issues. We have him in a position where he’s interacting with the least amount of people.”

But no one gave Brewington, 54, the boot until around 5:45 p.m. — after The Post made inquiries with the Board of Elections.

The drowsy poll worker denied sleeping on the job.

“This is the busiest polling station around,” he said. “It’s busy.”

Meanwhile, New Yorkers seethed about inaccurate voter rolls, being shut out of closed polling sites and showing up to stations that ran out of ballots.

Mayor de Blasio complained that voting lists in Brooklyn contained “numerous errors, including the purging of entire buildings and blocks of voters from voting lists.”

“The perception that numerous voters may have been disenfranchised undermines the integrity of the entire electoral process and must be fixed,” he said.

The mayor received reports that the purged lists were at polling stations at PS 5 in Bedford-Stuyvesant and PS 251 in East Flatbush, according to a City Hall source. Those communities have large minority populations that would likely vote for Hillary Clinton.

Two polling sites in Brooklyn — a senior center in Fort Greene and PS 73 in Bedford-Stuyvesant — failed to open for at least two hours.

A polling station at the Atlantic Terminal Senior Citizens Center didn’t open until 8:15 a.m. because the elections coordinator simply didn’t show up, according to a Board of Elections spokeswoman.

Vexed voters took to Twitter to voice their complaints.

“I have been here since 550 am.. Still cannot vote. Machines are not up and there are no paper ballots,” @LammyGwanBadSuh tweeted from a polling station at the Christopher Avenue Community School in Brownsville.

Former city GOP candidate for comptroller John Burnett said his Harlem polling place ran out of Republican ballots — and he was handed a Democratic ballot instead.

“CORRUPTION IN FULL FORCE in Harlem,” he tweeted.

He told The Post that a poll worker was directing Democrats to vote for Hillary Clinton delegates.

Democratic candidate Bernie Sanders slammed the city’s disorganized elections administration as a national embarrassment.

“From long lines and dramatic under-staffing to longtime voters being forced to cast provisional ballots and thousands of registered New Yorkers being dropped from the rolls, what’s happening today is a disgrace,” said Sanders spokesman Karthik Ganapathy.

State Attorney General Eric Schneiderman’s office received over 700 phone calls and e-mail complaints from voters across the state — many from people who lamented that they were not registered or not enrolled in a political party to vote in a presidential primary, or that they were being denied affidavit ballots.

Additional reporting by Kirstan Conley, Matthew Allan and Yoav Gonen