It's been a rough week for uptime. Google App Engine has been struggling with performance problems for hours, and appears to be down. The problems began at 6:30 a,m, Pacific time, when App Engine began experiencing high latency and error rates. "All applications accessing the Datastore are affected," Google said in a notice to developers. Shortly afterward the service went into "unplanned maintenance mode" and began operating as read-only, meaning developers couldn't update their apps. "Our engineering teams are looking into the root cause of the problem," Google said.
The App Engine Status Page is currently unavailable. The App Engine team is providing offsite updates via Twitter. UPDATE: At 3:15 Eastern, the status page is back: "Datastore read access has been reenabled and the team expects Datastore write access will be reenabled shortly."