Kakao Corp., which runs the country’s biggest mobile messenger KakaoTalk, suffered its worst-ever server outage over the weekend, which paralyzed messaging and other mobile services, illustrating the immense danger that could hit a tightly interconnected society when things go wrong.

KakaoTalk’s text, photo and video message services were disrupted after a fire broke out at the data center in Pangyo, just south of Seoul, at 3:30 p.m. Saturday. The blaze at the Pangyo data center, operated by SK C&C, led to the shutdown of electricity to Kakao’s servers, resulting in massive online service disruptions across the nation, ranging from messaging to taxi-hailing to mobile payment based on KakaoTalk.

The server outage lasted for over 10 hours and partial disruptions continued through Sunday. As Kakao restored 12,000 servers on Sunday afternoon, only text messages were restored, with other Kakao-affiliated services going through problems. Even on Monday, some users complained about delayed transmissions of messages on KakaoTalk.

The underlying reason for such large-scale damage lies in Kakao’s sprawling services based on its dominant messenger app. For starters, KakaoTalk is extensively used by Koreans. According to mobile data compiled by IGAWorks, KakaoTalk’s monthly active users stood at 43.2 million in June this year -- a virtual monopoly in the mobile messenger market in a nation whose population is 51.7 million.

Riding on the unbeatable popularity of KakaoTalk, Kakao has made inroads in a wide range of business sectors and emerged as a giant platform powerhouse with over 130 affiliates. Kakao currently controls 90 percent of the domestic taxi-hailing market, and its business clout is growing in shopping, mobile payment, digital content and commerce.

However, as the latest fire-induced server outage demonstrates, Kakao did not pay much attention to firming up safety and security solutions for its diverse services widely used by Koreans.

For instance, Naver, the country’s biggest online platform, also its servers hosted at the SK C&C Pangyo data center, but its service disruptions were fairly limited and recovery was swift. The reason was that Naver operates its own servers in Chuncheon, Gangwon Province, and scatters some of its servers in several spots around the nation. Unlike Naver, Kakao depends on the SK facilities, without securing enough backup servers and mapping out contingency plans.

The server outage marks Kakao’s sixth glitch this year alone, suggesting that the company is failing to run stable services. This raises questions about whether Korean users can rely on Kakao’s services that require a high level of security and seamless operations -- such as mobile payment and banking. Even though Kakao Bank had only partial disruptions for about two hours in connection with the fire accident largely because it runs its own data center, the Kakao-wide service glitch is serious enough to send shivers down the spine of many Kakao Bank users.

The damage could be much deeper and wider if a server outage takes place on a weekday, as millions of Koreans depend on KakaoTalk and its sprawling services for work and business.

President Yoon Suk-yeol said Monday the antitrust watchdog is looking into KakaoTalk’s dominance in the market, suggesting that the government may step in to address the structural flaws linked to Kakao’s monopoly over the country’s basic infrastructure.

Another important issue is to ensure the safety surrounding the data centers that host critical data and provide essential network backbones for online services. The number of data centers has jumped from 53 in 2000 to 156 in 2020, according to the Korea Data Center Council. Not only private firms but also state agencies are building or running data centers. However, safety measures against fire and other accidents are said to be insufficient, and the government has yet to propose a bill aimed at stepping up security for data centers.

Given that Kakao’s latest server outage lays bare on the fatal vulnerability of the tightly interconnected nation, policymakers need to introduce a policy that requires online firms and data center operators to strengthen security, prepare additional backups and update contingency plans.