Without seeing the actual data and code, I can only take a guess on the cause of the problem.
The error message should be "The coordinates or measures are out of bounds." rather than the other one you mentioned, NETWORK_E_EDIT_SESSION_IN_PROGRESS. The error code associated with this error message can be returned from various places in ArcGIS library. In addition to check the feature geometry's location in the coordinate system, the attributes measurement such as Z and M is also considered as the possible cause here. Also, if the geometry involves curve segment, like bezier, clothid, etc., can sometimes also causes this problem during the process.