The Spring ’17 sandbox preview window is scheduled to begin Jan 6, 2017. By Jan 6, 2017, you may need to take action to ensure your sandbox is active on a Spring ’17 preview instance rather than it remaining on Winter ’17. Read the Spring ’17 Sandbox Preview Instructions on the Salesforce Community site to determine if you need to …

As of Today we are seeing that the known Salesforce issue is looking to have been resolved. We will be monitoring this over the next few days, but so far all of our previous tests that returned a failure are all now passing.