Left to right: Adrian Charya, Ravi Ratnam, Param Sami,Jaynald Anand were part of the 30 per cent of people affected by the cashless issue at Hamilton's sevens tournament.

A problem with the Hamilton Sevens cashless system backed up bars on Saturday afternoon.

Pre-loaded wristbands were meant to speed up payment but ended up doing the opposite when a programming glitch struck.

But organiser Dallas Fisher says it was sorted around 4pm and won't be leaving punters thirsty on Sunday.

DOMINICO ZAPATA/STUFF Ethan Carter was able to get his beers but other Sevens-goers had problems with the cashless system.

It's the first cashless event involving New Zealand Rugby, which has seen previous tournaments overshadowed by drunken carnage.

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Punters are now required to wear bracelets loaded with money, and if they become too intoxicated they are cut off.

TOM LEE/STUFF The cashless issue was the cause of the big queues, said Sevens organiser Dallas Fisher, left. He's pictured with Sevens general manager Steve Dunbar (file photo).

While it worked fine for some, about 3500 people who had pre-loaded money struck trouble, Fisher said.

"It was enough to cause the problem of the queues," he said.

"The machine just ground to a semi-halt."

The problem took a while to figure out but turned out to be a programming issue in which one feature on the card was switching off the another necessary one.

"For the period that we didn't have it fixed it was unacceptable. Customers had to wait too long," Fisher said.

There were plenty of complaints on social media and, in the stadium, Adrian Charya was one of the frustrated punters who topped up his account and then found he couldn't buy anything.

"It's pretty embarrassing, standing in line and everybody looking at me like I didn't have any money."

"When you put like a couple of hundred bucks on your wristband, you've got to have some trust, right?"

Fortunately for Charya, someone came around to re-register his wristband and it started working again.

But he was also frustrated by the switch to light beer about 4pm.

What happens if someone finishes work at 5pm and turns up to watch a game, he asked.

Fisher was standing by the call to change to low-alcohol beverages, which was a planned move based on hourly reports on the volume of alcohol sold, and observations from those selling.

"You add those together and you make a decision," he said.

"In my view, we made absolutely appropriate decisions."

The call has to be for the whole crowd, he said, because they're trying to manage 23,000 people.

Cashless issues aside, he was giving the day a 9.5 out of 10.

Crowds arrived early, with a strong Pacific Island presence, he said, and ticket holders were making good use of the festival area.

There had also been good feedback from New Zealand and World Rugby, as well as the venue.

Eye-catching costumes included a group of prawns, Where's Wally and Billy T James.

Corporate groups got in on the act, he said.

For example, PwC had leis and tutus on the back of guest chairs for people who weren't dressed up.

Those costumes, the ambience of the early Pacific Island crowd and people enjoying themselves in Mill Street added up to make the day for Fisher.

"Then when the whole place filled up for the All Blacks versus Scotland, when the cheer went up."