By technology editor Ian Bush

PHILADELPHIA (CBS) — If you’re a Netflix subscriber who planned to watch some movies on Christmas Eve or as you opened presents this morning, there was no Elf or National Lampoon’s Christmas Vacation for you.

The online service suffered an outage of 20 hours.  And it was the worst time for a blank screen, with many new TVs and streaming devices being unwrapped on Christmas morning.

Netflix has apologized for the issue, which affected a swath of subscribers across North and South America starting about 4pm ET on Christmas Eve.  Many took to Twitter to complain.

Service was restored about noontime on Christmas Day.   Netflix tweeted its thanks to “awesome members” for being patient.

The streaming service runs on Amazon’s cloud.   Amazon’s data center in Virginia was having problems, but — notably — was not affecting Amazon “Prime Instant Video,” which competes with Netflix.

Amazon said its engineers were working to fix what was wrong.