The morning of July 17, Dîner en Blanc opened the final web registration for those wishing to attend its annual pop-up picnic on Aug. 21 in Philadelphia.

About 10,000 people on a waiting list attempted to log in - and swiftly crashed Dîner en Blanc's registration system, based at DEB's international headquarters in Montreal.

This was not the first time that the volunteer-run DEB has encountered online registration glitches over its now-third year in Philadelphia. The event itself - whose location is disclosed only moments before its start - has run smoothly. In 2012, 1,300 people dressed in white and carrying their tables, chairs and food took over Logan Circle. Last year, 2,500 people partied on the JFK Boulevard Bridge over the Schuylkill.

Among those thwarted that day was Chris Nowaczyk, a cancer researcher at the University of Pennsylvania. He had gotten in but was in the middle of registering when the system crashed.

Nowaczyk was peeved. On a day when Malaysian Airlines Flight 17 was blown out of the sky and the Middle East boiled over, shut-out picnicgoers vented their spleens on social media. (Sample: "This is the equivalent of Lucy setting up the football for Charlie Brown two years in a row and pulling it away at the last second.")

Nowaczyk decided to organize his own event, Dîner en Noir. He found like-minded people to help.

"This was born out of frustration," Nowaczyk said. "It was a spur of the moment thing. I felt excluded."

On the evening of Aug. 21, just as 3,500 people dressed in white will attend the sold-out Diner en Blanc at an undisclosed location, Nowaczyk and his crew plan to host 500 people dressed in black - with a splash of red (this year's color) - at Diner en Noir, also at an undisclosed location.

(Wouldn't it be a knee-slapper if both groups go to the same location?)

Dîner en Blanc Philadelphia co-founder Natanya DiBona called the situation "unfortunate."

She said she was logged into the system on July 17, watching in vain as the registration attempts by Nowaczyk and several others were disabled by the system. She said she reached out to ensure them that their registrations were valid, but they did not want to hear it.

Within hours, Nowaczyk and allies had registed and had set up a Facebook page, proclaiming a "revolution."

He also enlisted the DJ services of Robert Drake of WXPN.

The rhetoric seems to be less strident now as Noir closes in on its target of 250 tables for two. Noir is charging $50 for a table for two; it was charging $62 for seating at a communal table with chairs provided, but that arrangement is now sold out. A Diner en Blanc slot was $68.50 for two.

There is another difference. Diner en Blanc, which began more than 25 years ago in Paris, is a commercial enterprise run in its various cities by volunteers.

Diner en Noir, also staffed by volunteers, plans to donate all proceeds that exceed expenses to Philabundance, the Philadelphia hunger-relief group. Both Blanc and Noir have to pay for services, including legal and administrative work.

DiBona said: "I'm happy that they are celebrating the city, but I'm hurt by the assertion that this is for people we left out. It was a software glitch."

On social media, Diner en Blanc's critics call it "elitism," DiBona said. "That's unfair."

Next year, she said, Diner en Blanc would have a "whole new system."