Data view web part throwing error

Question

Hi I'm using a xslt based dataview webpart the steps i have taken to create a data view webpart is that

1. added a list view webpart on the page
2. Modified the toolbar property to show fulll toolbar
3. open the web page containing above list view webpart in sharepoint desginer and converted it to xslt based webpart (to make further changes in UI)
4. saved the page and previewed in browser

in browser web part was throwing the error while i was able to see it properly in desginer witout any error the error maesseged shown in webpart was:

Unable to display this Web Part. To troubleshoot the problem, open this Web page in a Windows SharePoint Services-compatible HTML editor such as Microsoft Office SharePoint Designer. If the problem persists, contact your Web server administrator.

The error message provided in sharepoint log file was :

05/12/2010 17:56:29.54    w3wp.exe (0x19FC)    0x1E9C    Windows SharePoint Services    Web Parts       89a1    Monitorable    Error while executing web part: System.NullReferenceException: Object reference not set to an instance of an object.
                                                                                                                                   at Microsoft.SharePoint.WebPartPages.DataFormWebPart.ResolveParameterValuesToXsl(ArgumentClassWrapper argList)
                                                                                                                                   at Microsoft.SharePoint.WebPartPages.DataFormWebPart.PrepareAndPerformTransform()
05/12/2010 17:56:29.62    w3wp.exe (0x19FC)    0x1E9C    Windows SharePoint Services    Web Controls    88wy    Medium         SPDataSourceView.ExecuteSelect() - selectArguments: IsEmpty=True, MaximumRows=0, RetrieveTotalRowCount=False, SortExpression=, StartRowIndex=0, TotalRowCount=-1
05/12/2010 17:56:29.62    w3wp.exe (0x19FC)    0x1E9C    Windows SharePoint Services    Web Controls    88x2    Medium         SPDataSourceView.ExecuteSelect() - formattedQuery = <Where><Eq><FieldRef Name="Featured"/><Value Type="Boolean">1</Value></Eq></Where>
05/12/2010 17:56:29.64    w3wp.exe (0x19FC)    0x1E9C    Windows SharePoint Services    Web Parts       89a1    Monitorable    Error while executing web part: System.NullReferenceException: Object reference not set to an instance of an object.
                                                                                                                                   at Microsoft.SharePoint.WebPartPages.DataFormWebPart.ResolveParameterValuesToXsl(ArgumentClassWrapper argList)
                                                                                                                                   at Microsoft.SharePoint.WebPartPages.DataFormWebPart.PrepareAndPerformTransform()

Answer 1

The cause for this problem is a Sharepoint 2007 Designer bug,if you create a DVWP in Sharpeoint designer 2007 it will append the GUID of the LIST in the code and would link to DVWP, if you try to create a new List it will always create a new GUID which will never match up with the DVWP and it breaks.

Solution: Open the page having problem in Sharepoint Designer 2007 Search for "ListID" and replace with "ListName" and change the "DefaultValue=" to your List name, this would fix it.

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