Google has apologised for causing its Google+ users to be spammed over the weekend, saying the fault was caused by a lack of disk space.
Google's senior vice-president of social, Vic Gundotra, said in a post on his Google+ wall that the + system resent notifications multiple times to users.
"Please accept our apologies for the spam we caused this afternoon," Gundotra said in the post.
"For about 80 minutes we ran out of disk space on the service that keeps track of notifications. Hence our system continued to try sending notifications. Over, and over again. Yikes."
Gundotra said Google didn't expect to hit capacity for Google+ as quickly as it did, but that the company should have been prepared despite this.
The rollout of Google+ last week was praised by privacy experts for its deliberate and measured nature, with some saying Google has learnt its lesson since the US Federal Trade Commission punished the company for privacy violations.