According to Incapsula's status page, here is their explanation:
A rare edge case triggered an error on the Incapsula service and caused a system wide ripple effect making sites inaccessible. The issue was identified immediately and corrective actions were taken to restore service levels.Besides this issue, there is another issue I am dealing with in regards to the way Incapsula handles SSL certificates for legacy clients. By legacy clients, I mean clients that still use IE6 or some other application that doesn't support SNI. For clients that support SNI, Incapsula hands them our SSL certificate, and if the client doesn't support SNI then Incapsula hands them their SSL certificate. Why? Who knows?!
You might be thinking to yourself, why would that matter? Well, it matters if you have clients that use Java based applications that don't support SNI, and are configured to manually trust SSL certificates instead of trusting the certificate authority. It would be less of an issue if Incapsula's SSL certificates lasted a year or so, but they renew themselves every two months! It's a nightmare!
Needless to say, we are pretty frustrated with Incapsula at the moment. If you are thinking about using them you might consider another CDN provider like Akamai or CloudFlare.
Do you use Incapsula? Were you impacted last night? Let us know in the comments.