Description
The annotation feature class being upgraded is missing an annotation class or a symbol collection.
This can happen if the annotation feature class was originally created in ArcGIS 8.x and was not updated to the 9.x schema, or if the annotation feature class was created programmatically and the annotation class or symbol collection was not added.
Solution
Before upgrading this annotation feature class in ArcGIS Pro with the Upgrade Dataset tool, use the Update Annotation Feature Class tool in ArcMap to update the schema of the annotation feature class.