The connection point "filter parameter" on does not allow multiple connections

Question

I have a custom web part which does not allow multiple connection. Scenario : I've added the custom web part on the page, added 2 lists on the same page.

Step 1 : I connect List 1 to web part and implement my functionality

Step 2 : I delete List 1

Step 3 : I get my custom error message that list name is invalid.[As required for the functionality]

Step 4 : I edit web part , and try to connect it to List 2

Step 5 : Error message received

"The connection point "filter parameter" on "g_789a749a_836c_45c4_b247_f4bfa28b94a3" does not allow multiple connections.

Stack Trace

WebPartPageUserException: The connection point "filter parameter" on "g_789a749a_836c_45c4_b247_f4bfa28b94a3" does not allow multiple connections. Microsoft.SharePoint.WebPartPages.SPWebPartManager.CanSPConnectWebPartsCore(WebPart provider, ProviderConnectionPoint providerConnectionPoint, WebPart consumer, ConsumerConnectionPoint consumerConnectionPoint, WebPartTransformer transformer, Boolean throwOnError) +2369 Microsoft.SharePoint.WebPartPages.SPWebPartManager.SPConnectWebParts(WebPart provider, ProviderConnectionPoint providerConnectionPoint, WebPart consumer, ConsumerConnectionPoint consumerConnectionPoint, WebPartTransformer transformer, Boolean bCheck) +96 Microsoft.SharePoint.WebPartPages.Communication.PersistConnection.CreateConnection(String xFormTypeName, String xFormInfo) +630 Microsoft.SharePoint.WebPartPages.Communication.PersistConnection..ctor(ConnectionDesigner designer, SPWebPartManager manager) +1517 Microsoft.SharePoint.WebPartPages.Communication.ConnectionDesigner.PersistChangedConnections() +63 Microsoft.SharePoint.WebPartPages.SPWebPartManager.CreateConnectionDesigner() +437 Microsoft.SharePoint.WebPartPages.SPWebPartManager.ActivateConnections() +361 System.Web.UI.WebControls.WebParts.WebPartManager.OnPageLoadComplete(Object sender, EventArgs e) +70 System.EventHandler.Invoke(Object sender, EventArgs e) +0 System.Web.UI.Page.OnLoadComplete(EventArgs e) +11046222 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3160

I am think of checking weather the web part has any connection or could be connected to the list.

Answer 1

I fixed it by adding AllowsMultipleConnections:

[ConnectionConsumer("Filter", "UniqueFilterName", AllowsMultipleConnections = true)]
public void GetConnectionInterface(IWebPartParameters pProvider)
{
}