By: Ethan Wilansky, Stefan Kowalewski, and Tomek Stojecki

We have been working with SharePoint 2010 Business Connectivity Services (BCS) in Visual Studio 2010 for a while now and have run into some technical challenges along the way. Not much has been posted about the specific challenges we've faced, so we figured it would be useful to post some concise content describing the issue and our resolution.

If you're brand new to BCS and are more interested in SharePoint Designer (SPD)-created BCS Solutions or your BCS solution can be built in SPD, these posts will be less useful to you.

If, on the other hand, you are developing BCS solutions in Visual Studio, you've come to the right place. Without further ado, here's our first finding:

Problem: You deploy an external list that you created with a Visual Studio developed external content type. When you attempt to create or update a new item in an external list, you receive an error message: "Data Source Conflict: Your changes conflict with those made concurrently by another user. Refresh the form and submit your changes again."

Possible Solution: In your Visual Studio 2010 BCS project, find the Create or Update method that's failing. Verify that each of the fields in your input type descriptor have the Creator property (for the Create method) or Updater property (for the Update method) set to True. Note, this property should not be set to true for the identifier field if the Line of Business Application (LOB) auto generates the value.

Editor's Note: Email "the 3 Poles" if you have any otherĀ  BCS/VS questions you'd like answered. Click their names in the byline for their email addresses. We'll have more of their "findings" next week!

See all the SharePoint Q&As:

Sharepoint Q&A: How do I display a more user-friendly error message?

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