Several readers have noted a strange error message appearing when trying to perform software updates from the Mac App Store.
Swscan.apple.com is one of several servers that Software Update uses to communicate with Apple. The apparent problem is that the security certificate for the server appears to have expired. Originally valid from May 22, 2012 to May 24, 2014. This is a problem that Apple will need to fix on their side. In the meanwhile, users can manually download updates from Apple’s support site.An Error has occurred
The certificate for this server is invalid. You might be connecting to a server that is pretending to be „swscan.apple.com“ which could put you confidential information at risk.
This article is from – Apple Forgets to Renew SSL Certificate, Breaking OS X Software Update