YouTube restored its mobile and web services approximately one hour after a widespread access disruption occurred.
On the 18th, YouTube announced regarding the morning outage: "A recommendation system issue prevented videos from appearing on all YouTube surfaces, including the homepage, app, YouTube Music, and YouTube Kids." The company added, "The homepage has been restored, and we are working toward a complete resolution."
Google Korea reported the homepage display disruption to the Ministry of Science and ICT at approximately 10:03 a.m. Service was normalized around 11:07 a.m., roughly one hour later.
The outage partially affected YouTube Music's search function, though users could still search and watch videos through their existing viewing history.
YouTube attributed the incident to a data indexing error on the homepage during a service update and said it is investigating the detailed cause. Data indexing refers to the process of creating an address directory (index) in advance to locate specific data.
YouTube normalized the homepage by blocking the problematic data and notified users of the service restoration through its official blog and social media channels.