When performing an operation involving business data (also called external data), Sharegate displays the following error:
SharePoint encountered an internal error in the Business Data service. This is often due to a wrong configuration of the Alternate Access Mappings.
|Any error code ending with: -153|
This error occurs because the SharePoint server encountered an internal error while executing a business data operation (such as trying to find a value). The most common cause for this internal error is when the service is accessed through an address that is not listed in the Alternate Access Mappings. For example, if you entered the IP address of the server in Sharegate, but there is no entry for the IP address in the Alternate Access Mappings, you would receive this error.
Verify the Alternate Access Mappings configuration in the SharePoint Central Administration and make sure that the address you use in Sharegate is listed there. You can read more about this here.
If everything seems correctly configured in the Alternate Access Mappings, have a look at the SharePoint ULS logs. They should contain more details about what is causing the internal error.