I did this for years without any issue until today. I cannot figure it out what is the problem I got today.
(1) I have a New Item custom form. I hide the default web part, insert a custom web part (a vs solution) and a content editor. Add a block of javascript to hide the left side navigation.
(2) At this point, everything still works fine.
(3) I need to hide ribbonrow via SharePoint designer which I cannot do in (1) because I cannot save the page with ribbonrow.
(4) After I save the page/form in SharePoint designer, I got the following error. As long as I do an "edit & save" even I do not make a change.
I also tried to deploy the old solution code, same result. The only change I can remember is we apply hotfix
KB Article Number(s): 2910943. I am not sure this make a different. I very appreciate if someone can help me out.
++++++++++++++++++++++++++++++++++++++++++++
Web Part Error: An unexpected error has occurred. Correlation ID: d05e219d-b6e7-30d7-35ec-aea40e50210e.
[NullReferenceException: Object reference not set to an instance of an object.]
at Inventory.InventoryForm.InventoryForm.EnsureScriptManager()
at Inventory.InventoryForm.InventoryForm.OnInit(EventArgs e)
at System.Web.UI.Control.InitRecursive(Control namingContainer)
at System.Web.UI.Control.AddedControl(Control control, Int32 index)
at Microsoft.Web.Design.Server.ServerDocument.Microsoft.Web.Design.Server.IServerDocumentDesigner.ParseControl(String outerHtml)
at Microsoft.SharePoint.WebPartPages.SPWebPartManager.CompressUsingMicrosoftWebDesigner(SourceContent sourceContent, String allRegisterDirectives)
at Microsoft.SharePoint.WebPartPages.SPWebPartManager.CompressInOrder(Deserializer firstMethod, Deserializer secondMethod, SourceContent sourceContent, String allRegisterDirectives, Boolean isClosed)