CloudFlare update states:
Identified - The issue has been identified and a fix is being implemented.
Jul 1, 01:09 UTC
Posted Jun 30, 2015 - 19:10 MDT
Monitoring
Cloudflare, our DNS and CDN provider, is currently "Investigating Network Related Issues in multiple colos." This is resulting in elevated 5XX errors for visitors in some regions. They expect to have issues resolved soon.