The layer type or data source is not supported in 9.3.1 packages. These items will not be available when the package is opened by previous versions of the software.
Solutions
- Replace the layer with a supported layer type for that version of ArcGIS.
- Alternatively, remove the layer from your package.
More information
With each release of the software, new layer types and data sources are available and will not be supported by previous versions of the software. Map and layer packages support multiple versions of ArcGIS; therefore, consider the layers and data sources you are choosing to package to ensure they are available in previous versions of the software. Packaging unsupported layers and datasets for previous versions will result in those items not opening when used by previous versions of the software.