Exception : The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases.

Issue

This error can occur when Bamboo Data Viewer is added to a custom master page.

Resolution

1. Using SharePoint Designer edit the custom master page.
2. Locate the following lines in the <Head/> section
   
   <!--MS:<SharePoint:AjaxDelta id="DeltaSPWebPartManager" runat="server">-->
               <!--MS:<WebPartPages:SPWebPartManager runat="server">-->
               <!--ME:</WebPartPages:SPWebPartManager>-->
           <!--ME:</SharePoint:AjaxDelta>-->
   
3. Remove (cut) them from the <Head/> section
4. Place (paste) them into the <Body/>
5. Save the master page changes in SharePoint Designer

A sample corrected master page is attached.