This layer is related to another layer by a relationship class and cannot be edited with an ArcGIS for Desktop Basic license.
Solution: Upgrade your license to ArcGIS for Desktop Standard or ArcGIS for Desktop Advanced.
More information: With an ArcGIS for Desktop Basic license, you receive this error when you attempt to start editing a feature class that is related to another feature class or table. In addition, it appears if you attempt to edit feature-linked annotation, since a relationship class is used to maintain the link between the origin feature and its annotation.
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