The country's main digital vaccination authentication system momentarily shut down on Monday, inciting significant confusion among users who could not pull up their vaccination or PCR test records.

Monday marked the first day of the expanded COVID-19 pass system after a week-long grace period expired, enabling fines to be issued for rule-breakers. 

Reports began to pour in nationwide of people unable to access COOV, a smartphone app operated by the Korea Disease Control and Prevention Agency(KDCA) that offers vaccination certification, from around 11:40 a.m.

Apps by Naver, Kakao Talk and Toss Bank, which produce a QR code linked to COOV, also saw spotty service around the same time.

The outage caused delays as it came around lunch time when people needed to flash their QR codes to enter restaurants and cafes. Some reportedly wrote down their information and went in as a measure of last resort, which is not allowed under the expanded system.

KDCA has apologized, saying the sudden server overload caused inconveniences and that related agencies are holding emergency talks on the matter.