Sometimes, when editing a data flow, you'll get an error that says, "Unable to retrieve the data flow top level element corresponding to the execution-session. No element found at provided locator." It will appear in a dialog like the following:
You will most typically experience this error if you are quickly adding or removing nodes to a data flow. After it is first seen, this error will occur when you open the data flow or attempt to edit it. It will typically persist through closing and opening the data flow along with exporting and reimporting the data flow.
If you experience this error, the easiest way to solve this issue on its own is to upgrade. Version 3.1.3 and newer addresses a number of situations in which this error would occur. However, if you are on the latest version, we recommend that you submit a ticket to Support along with your log files so that we can step you through a solution.