On December 5th at approximately 12:05 pm, our alerting system detected an issue with a portion of Pantheon sites being able to serve uncached PHP requests. Our investigation revealed the deployment process we use to keep customer PHP versions up to date caused some sites to be unable to start PHP. This resulted in a number of sites being unable to process PHP requests.
Maintaining current version of PHP is a critical part of the service we provide our customers. We have identified improvements that will prevent this type of error from recurring and allow us to resolve issues more effectively in the future. We understand customers trust Pantheon to provide a reliable development and operating environment. We apologize for the issues our customers were experiencing during this incident.