Since the sandbox update to Spring '15, our sandbox has been unable to save in the Developer Console. We can open items (classes, pages, etc) but when we try to save them, we get "Failed to create createContainerMember for containerId=undefined: null is not a valid containerId" errors and they do not save.

We have tried the resolution found in this solution: https://help.salesforce.com/apex/HTViewSolution?id=000204953&language=en_US
but creating a new Workspace does not work (as in the Workspace is not created) and it does not fix the save issue. 
We have also tried switching workspaces, which also does not work.

We have cleared cache and tried on multiple computers from multiple networks.