The service could not be reached from about 5:20 p.m. to about 5:50 p.m. EST, SlashGear reported.
"Some people encountered errors, or a slower-than-normal experience on YouTube today," the video service said in a statement. "We worked quickly to address the issue and fixed the problem. We're sorry for any inconvenience this caused."
Attempts to access YouTube during the outage resulted in a "500 internal server error" message, indicating the sites' servers were down.
The outage also affected playback on mobile as well as connected devices, and YouTube embeds on third party sites were also unavailable.