By Ethan Wilansky, Stefan Kowalewski, and Tomek Stojecki
When you attempt to create an external list, SharePoint throws an unspecified ASP.NET error, which you can see in Figure 1.
In addition, the following errors appear in the SharePoint Unified Logging Service (ULS) (see Table 1).
Open the site in SharePoint Designer (SPD) and see if you can find the list under Lists and Libraries. If the list fails to get created, it will be hidden and available through SPD.
Delete the list and attempt to create the list again in either SPD or through the browser. If you use the browser, you might have to navigate away from the create list page in order to recreate the list after deleting it in SPD.
See all the SharePoint Q&As:
Sharepoint Q&A: How Can I Create an External List When SharePoint Throws an Unspecfied ASP.NET Error?
Sharepoint Q&A: How Can I Create an Action for an External Content Type in SharePoint?
Sharepoint Q&A: How to Make a Type String Type Descriptor a Required Field in the BDC Explorer
Sharepoint Q&A: Data Source Conflict