I want to add my custom web part in master page using SharePoint Designer.

I tried but I am receiving the error shown below.

enter image description here

And this is the description of error.

ExecuteRequestInSandBox call failed. System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.SharePoint.WebPartPages.BinaryWebPartSerializer.Serialize(PersonalizationScope scope, BinaryWebPartSerializerFlag binaryWebPartSerializerFlags, BinaryWebPartSerializerWriter writer) at Microsoft.SharePoint.WebPartPages.BinaryWebPartSerializer.Serialize(SerializationMode mode, BinaryWebPartSerializerFlag binaryWebPartSerializerFlags, BinaryWebPartSerializerWriter writer) at Microsoft.SharePoint.WebPartPages.SPUserCodeWebPart.EnsurePersistedBlobsMatchPropertiesCollection() at Microsoft.SharePoint.WebPartPages.SPUserCodeWebPart.GetWebPartDataForRemoteCall(Object& viewState, Object& controlState) at Microsoft.SharePoint.UserCode.SPUserCodeWebPartRemoteExecutionHelper.ExecuteRequestInSandBox(HttpContext context, SPWeb web, SPWebPartManager manager, SPUserCodeWebPart userCodeWebPart)

enter image description here

  • What/how did you try to add your custom web part? Commented Apr 5, 2016 at 7:27
  • How did you added web part in master page? Can you provide some code ? Commented Apr 5, 2016 at 8:24
  • enjoysharepoint.com/Forum/Details/…
    – Madhav
    Commented Apr 5, 2016 at 8:50
  • i followed the link mension to add as above for adding web part to master page,and i also tried same with the designer option using browser where we are using snippet section to get html of web part to place in html page associated to a master page like seattle.html and seattle.master where added the code web part in.html page but there also it shows the same error
    – Madhav
    Commented Apr 5, 2016 at 8:54
  • Try this: ukreddysharepoint2010.blogspot.in/2014/05/…
    – P S
    Commented Apr 5, 2016 at 10:27

1 Answer 1


Get full qualified assembly of SharePoint solution from visual studio using following steps:

Open Visual Studio
Go to Tools –> External Tools –> Add
    Title: Get Qualified Assembly Name
    Command: Powershell.exe
    Arguments: -command "[System.Reflection.AssemblyName]::GetAssemblyName(\"$(TargetPath)\").FullName"
    Check "Use Output Window".

Register webpart in master page like:

<%@ Register TagPrefix="WpNs" Namespace="SPDemo.NewWebpart" Assembly="SPDemo, Version=, Culture=neutral, PublicKeyToken=2c5bae03c7cf380a"%>

Add webpart where you want to add like:

<WpNs:NewWebpart ID="testid" runat="server"></WpNs:NewWebpart>

It will work

  • Thank You so much for your kind reply, the article i have followed i.e enjoysharepoint.com/Forum/Details/… this article also tells the same way as you mentiond,but still i followed your steps as you said but no change in result.
    – Madhav
    Commented Apr 5, 2016 at 11:15
  • Yes, you have done that. But deploy solution globally and verify your fully qualified assembly. Before few days, i have already done this.It's worked perfectly. That's why i am replying you again. Commented Apr 5, 2016 at 11:22
  • my bad luck ,it's not working.but thank you Viraj
    – Madhav
    Commented Apr 5, 2016 at 11:44
  • Welcome. Can you post here your registration code line and webpart line? Commented Apr 5, 2016 at 11:46
  • this is the registration line <%@ Register TagPrefix="WpNs0" Namespace="Microsoft.SharePoint.WebPartPages" Assembly="Microsoft.SharePoint, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
    – Madhav
    Commented Apr 5, 2016 at 12:16

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