On each resource event, the Orchestration service stores the current properties of the resource to enable debugging and auditing of the stack's history. However, the Orchestration service can only store 64kB (encoded) of such information. As such, if a stack contained a resource with particularly large properties (for example, a SoftwareConfig with a large script), the Orchestration service could not record events for the resource in questions, thereby preventing the stack from being created.
With this release, properties that are too large to store in the event table are elided. This, in turn, allows users to create stacks regardless of the size of each resources' properties.