More than a decade after the Y2K scare, a single extra second has caused problems for a number of notable web companies. The
leap second — a one-second adjustment added to atomic clocks to synchronize it with clocks based on the Earth's rotation — occurred on Saturday night and caught a number of companies unaware.
Reddit tweeted that it was having Java/Cassandra issues due to the extra second, while Mozilla
filed a bug report also due to leap second-related Java issues.