00274: Multipoint layer type is not supported in web scene
You are either sharing a web scene that contains a multipoint layer or are sharing a multipoint layer as a web scene layer. Multipoint layers cannot be drawn as part of a web scene.
Solutions
If you are sharing a web scene, remove the multipoint layer from the scene.
If you are share a web scene layer, use the Multipart To Singlepart tool to separate the parts.