I would start looking at the events of the entity that you are syncing.
Is there an action on before/after commit that commits the object, leading to a stack overflow?
The second error, is a warning stating that the client is requesting more than 100 objects from the sever which might cause a degradation of performance. This does not look to be related to the error, but might be if a loop is created in your app logic. However then this is a side effect and not the cuase for the stackoverflow.