Visual Studio 2019: SharePoint 2010 Visual Webpart issue
Now days I have to use the modern Visual Studio 2019 to update the old SharePoint 2010 web site to meet the AODA accessibility standard. Issue 1: ScriptManager and UpdatePanel not found in namespace System.Web.UI Solution: Firstly locate the project where <asp:ScriptManager> is used. Usually it's used in the master page (in the branding project). Then add a reference to the assembly System.Web.Extensions . Select Project-> Add Reference and then select the assembly name. https://stackoverflow.com/questions/19122286/scriptmanager-and-updatepanel-not-found-in-namespace-system-web-ui Issue 2 The auto-generated webart.ascx.g.cs is missing 1. The “Site URL” property of your project The “Site URL” property of your project should be correct. 2. Click on the *.ascx and see its property The “Custom Tool” property should be set to “SharePointWebPartCodeGenerator” value. Configure properties, save *.ascx, make any temporary changes to *.ascx file, save again and PUFFFF !!!! the *