There is a key difference between the import metadata and the ‘Sync with VDP’ operations performed in this scenario. The ‘Sync with VDP’ option enables the Data Catalog to synchronize the metadata of Virtual DataPort elements such as views, web services, etc whereas importing the metadata zip file in Denodo Catalog will bring in Data Catalog specific elements such as Tags, Categories and Property Groups.
In general, the ‘Internal error while executing operation!’ error in the Data Catalog occurs when there is a connection issue with the Virtual DataPort which is unable to retrieve the required results.
In order to troubleshoot this scenario, I would do the following steps:
1. Verify if the Virtual DataPort Server is running so that the views can be accessed from the Data Catalog.
1. Check the entries in the **vdp-data-catalog.log** file under the <DENODO_HOME>\logs\vdp-data-catalog directory for possible error reasons.
1. Furthermore, you could try executing the corresponding view in Virtual DataPort Administration Tool or Web Design Studio and check the execution trace.
For more information on import/export or synchronizing metadata in the Data Catalog you could refer to the [Import and Export Data Catalog Metadata](https://community.denodo.com/docs/html/browse/latest/en/vdp/data_catalog/administration/import_export/import_export) and [Synchronize with Virtual DataPort](https://community.denodo.com/docs/html/browse/latest/en/vdp/data_catalog/administration/synchronize/synchronize#) sections of the Data Catalog Administration Guide.
Hope this helps!