Skype outage blamed on bug in older software version


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Skype’s outage last week is was caused by a bug in an older version of its software, used by more than half of its users, that overloaded its servers.

Lars Rabbe, Skype’s chief information officer, said on the Internet calling company’s blog that its ‘Skype for Windows client (version 5.0.0152)’ servers crashed last Wednesday and Thursday after a group of servers responsible for offline messaging became overloaded.


Newer versions of Skype’s software, such as version, and older versions of Skype were not affected by the initial problem, Rabbe said.

But because so many Skype users had version 5.0.0152, the server crashes caused about 25% to 30% of the company’s ‘supernode’ computers -- which serve as connection points in its network -- to fail. That caused users of other versions to fall victim to the outage as well, he said.

Skype has released a software update for version 5.0.0152 in an effort to keep such an outage from happening again.

‘We are learning the lessons we can from this incident and reviewing our processes and procedures, looking in particular for ways in which we can detect problems more quickly to potentially avoid such outages altogether, and ways to recover the system more rapidly after a failure,’ Rabbe said.

The blog post ended with an apology to customers -- which comes after the decision to reimburse paying Skype users affected in the outage.

‘We know how much you rely on Skype, and we know that we fell short in both fulfilling your expectations and communicating with you during this incident,’ Rabbe said. ‘Lessons will be learned and we will use this as an opportunity to identify and introduce areas of improvement to our software, further assess and invest in capacity and stability, and develop better processes for outage recovery and communications to our user base.’



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-- Nathan Olivarez-Giles