In a blog post on Wednesday, Skype offered up a post-mortem explanation to the recent outage that affected thousands of users who were unable to connect and communicate.
"For starters, it helps to understand that Skype is based on a peer-to-peer (P2P) network, which is explained here. Last week, the P2P network became unstable and suffered a critical failure," Skype explains.
"Users running either the latest Skype for Windows (version 184.108.40.206), older versions of Skype for Windows (4.0 versions), Skype for Mac, Skype for iPhone, Skype on your TV, and Skype Connect or Skype Manager for enterprises were not affected by this initial problem.
"However, around 50 percent of all Skype users globally were running the 220.127.116.11 version of Skype for Windows, and the crashes caused approximately 40 percent of those clients to fail. These clients included 25-30 percent of the publicly available supernodes, also failed as a result of this problem."
In other words, users should be pointing the finger partially at themselves for running outdated software, though Skype wasn't as blunt about this. Instead, the company said it's looking into several ways to avoid something like this from happening again, including revamping its process for automatic updates and continuing to invest in capacity upgrades.