San Diego Comic-Cons biggest registration day was halted Saturday because of technical issues and will need to be rescheduled.

Comic-Con held what it calls its open registration Saturday starting at 9 a.m., but it was halted 37 minutes later because organizers said there was an unforeseen anomaly with its registration system.

As of Monday afternoon, Comic-Con had yet to announce when registration would be rescheduled. It also had not fully discovered what caused the issues.

Our registration company is currently working to resolve the issue, said Comic-Con spokesperson David Glanzer, and has brought in additional personnel to investigate this matter.

Open registration is the last chance for fans to get one of the highly sought-after badges for a four-day event that accommodates roughly 130,000 attendees. The Saturday sale followed something called returning registration in late September, which was open to only those people who had paid tickets to last years convention. Open registration was for all the remaining tickets, although Comic-Con would not divulge how many were left.

This years Comic-Con International is scheduled for July 24-27, with Preview Night on July 23.

Complaints over the registration process flooded social media. On X, users criticized the organization for having a website that looked like it was from the 1800s and fumed when they finally got to the purchase screen, only to have the website freeze. Some posted pictures of burning dumpsters and smashed computers to describe the process.

I guess an apology from them would be too much to ask for, right? wrote one X user.

Mark Alvarado, 40, an illustrator in Austin, Texas, said he logged into Comic-Cons website around 8:20 a.m. Saturday. Like all users, he got a digital toucan bird — SDCCs mascot — that was supposed to move along a status bar as he got closer to making a purchase.

I maintain my toucan was perpetually injured, he said, laughing. It just wouldnt walk or move.

Alvarado gets to go to the convention anyway because he is a professional, having drawn Star Trek covers for San Diego-based comic company IDW and other projects. However, he was in line to get a ticket for his 13-year-old daughter and has tried to purchase in the general sale several times. He was successful last year getting tickets for his brother.

To be fair, Comic-Con always has some sort of hiccup, Alvarado said. Honestly, I just kind of shrugged (on Saturday). The reality is people at Comic-Con try their best and its not as if they are handling the sale themselves. At least they were smart enough to shut it down when it needed to get shut down.

Comic-Con is not alone in online ticket woes. The most high-profile blunder in recent memory was Taylor Swifts sale for her stadium tour last summer. Ticketmaster gave out a special code for verified fans, but many users reported being repeatedly kicked out of the system as they came closer to being able to make a purchase. The process went so poorly that a group of fans sued Ticketmaster.

Locals trying to buy Padres tickets had similar issues during the teams recent playoff run. Season ticket holders, and those with special codes as part of other promotions, faced disappearing seats as they went to make purchases. Tickets would appear but, often, after a user clicked on them, they were told the seats were no longer available.

Sam Malek, a software engineering professor at UC Irvine and president of software witness consulting firm Cyberonix, said websites can run into issues when they are overwhelmed by thousands of users and dont have enough processing power. While he didnt know Comic-Cons specific issue, he said a way for companies to prevent a crash is to use a cloud-based server like Amazon Web Services.

Malek said ticketing websites need to perform hundreds of calculations, which can affect computer processing ability. If a company is just using its own limited server network, it could crash. The advantage of a cloud-based service is it creates something called elastic computing, which allows for websites to scale up their processing power to meet demand and only pay for what is used.

So, instead of using your own hardware, you host your website on the cloud, he said. The thing about Amazon is they have thousands of servers.

While Comic-Con was tight-lipped on specifics of the issues, it did say it regretted how Saturday went down.

We apologize for the frustration this has caused, the organization said in a statement, and we thank you very much for your patience while they work to resolve the problem.