Who knew that a hashtag could cause such confusion?

All because of a simple hashtag, the owners of BluNotes of Charlotte were left trying to pacify customers early Sunday after an event that was supposed to feature R&B singer Case went totally haywire.

All because of a hashtag, the singer, in town for an album “listening event,” is accusing BluNotes’ owners of deception.

And all because of a hashtag, the two sides late Sunday were locked in a very public war of words on the BluNotes Facebook page.

Here’s what we know:

The owners of BluNotes, looking to book some talent, decided that Case would be a good fit for the University City nightclub/restaurant.

The 41-year-old singer who grew up in New York City had achieved some moderate success in the late 1990s with hits such as “Touch Me, Tease Me,” “Missing You” and “Happily Ever After.” In recent years, however, his record sales had cooled.

But with a new album on the market – “Love Jones, Vol. 1” – Case agreed to travel to Charlotte for the “listening event” at BluNotes.

Oscar Frazier, one of the BluNotes owners, said the club paid Case $5,000 for the appearance, plus travel expenses, lodging, free bottles (Gray Goose) and his choice of food.

Frazier said that based on talks with the singer’s manager, he was led to believe that Case, at a minimum, would come on stage to talk with fans about his new music. And at best, Frazier said, he thought the singer might even perform a cut or two.

But much to the chagrin of many, nothing like that happened.

When Case and his entourage arrived at BluNotes, sometime around 11:30 p.m., Frazier said, they went into a VIP room that had been set up for them.

And there they stayed – until about 12:30, when the singer’s DJ got on stage and said that Case would be coming out shortly.

At about 1 a.m., according to Frazier, Case did get on stage, but he said only one sentence: “I don’t know what y’all have been told, but I’m not performing.” And then he left, returning to his VIP room, where words were exchanged with BluNotes management.

According to Frazier, the singer said he was upset because BluNotes had used the hashtag “#performinglive” in some of its promotional material. (The contract, apparently, had prohibited such language.)

Frazier said he asked Case why his management team had not objected to the hashtag sooner – days earlier, in fact — in time for it to be taken down.

Meanwhile, Frazier said, patrons waiting to hear the singer were shocked and increasingly restless, some accusing the establishment of “bait and switch.”

Case could not be reached for comment, but in a post to the BluNotes Facebook page, the singer attached a screenshot of a partial document that seemed to prohibit the nightclub from making the claim of a live performance.

Frazier said he and his staff absorbed “all types of language from people that wanted to express their frustrations.”

Frazier said five or six people demanded their money back. Others were satisfied to get a few complementary items, he said.

Sometime around midday Sunday, BluNotes posted a full-throated apology for the “unfortunate event” and chalked it up to “miscommunication.”

But Case wasn’t done. On the BluNotes Facebook page, he posted several responses sprinkled with profanity and accusations of deceit.

“There can’t be any miscommunication because it’s all on paper,” he said in one. “Second I don’t perform NOWHERE, EVER , for 5K.”

As for the fans caught in the middle, some seemed to side with Case and accused BluNotes of trying to wriggle out of its own blunder. Others said the singer acted unprofessionally and showed disrespect for his audience.

One fan wrote a Facebook post suggesting that Case hire a public relations agent: “Last night was a bad look. Your fans simply wanted to hear you sing… A true professional would have picked up the mic and dropped a few bars no matter what was going on behind the scenes.”

As for lessons learned, Frazier said that going forward he’ll insist on clearer contracts.

He said he made what he thought were reasonable assumptions based on a rider to the contract that called for the club to provide Case with a one-hour soundcheck and a variety of electronic equipment typically associated with a live performance.

“I felt like people needed to know the full backdrop,” he told Qcitymetro late Sunday. “I’ve really been trying to toggle with what we could have done differently.”

Founder and publisher of Qcitymetro, Glenn has worked at newspapers including the Los Angeles Times, St. Petersburg (Fla.) Times, Philadelphia Inquirer, Wall Street Journal and The Charlotte Observer.