Description
The target and update layers must be the same type of web scene layer. For example, if the target layer is a building scene layer, the update layer must also be a building scene layer. See What is a scene layer? to learn more about the types of scene layers.
Solution
Choose a different update layer that matches the target layer type. Alternatively, choose a different target layer that matches the update layer type.
See Replace a web scene layer for more information.