The government's digital vaccine pass system malfunctioned for the second day on Tuesday, leading to a number of access failures during lunch time despite the addition of emergency servers to deal with heavy user traffic.

COOV, a government smartphone application that authenticates users' vaccination status by QR codes, along with affiliated third party programs, such as Naver and Kakao talk, has been plagued with major connection issues since Monday, the first day of the government's vaccine pass enforcement, as a result of heavy traffic.

The Korea Disease Control and Prevention Agency said it added emergency servers to the system overnight to deal with increased traffic, but many workers and restaurants in Seoul's office-heavy districts continued to experience outages for the second day around lunch time.

"I normally use the shake function on my Naver app to authenticate my vaccination, but it failed to work properly," a 60-year-old office worker surnamed Lim, who works in Yeouido, western Seoul, said.

Lim said he was finally able to enter a restaurant by authenticating his status using the Kakao Talk app.

"I was dumbfounded after the QR codes failed to appear both on the Kakao Talk and Naver applications," 27-year-old cram school instructor surnamed Shin said.

Shin said the government's vaccine pass system seemed under prepared as of now, and added she plans to visit her local community center to get a sticker proving her vaccination status before heading to work.

Many restaurant and cafe owners were also infuriated by the extended outage. Businesses can be fined 1.5 million won ($1,260) if they fail to abide by the vaccine pass system.

"I'm worried over potential connection errors continuing today," 30-something Japanese restaurant owner surnamed Kim said.

He recalled his experience of keeping customers in line due to the connection issue on Monday as being "warlike." (Yonhap)