Updating the Default Settings file in a WinForms .NET 5 Visual Basic app fails.

Visual Studio Version: >=16.8 Summary: Attempting to save after changing a value in the Default Settings file of a WinForms .NET 5 Visual Basic app fails.

Steps to Reproduce:

1. Create a new .NET 5 WinForms App.
2. Insert a new App.Config to the project by chosing Add/New Items and General/Application Configuration File.
3. Show All Files in the Solution Explorer and select the My Project branch.
4. Insert a new Settings file to the project by choosing Add/New Items and General/Settings File. Make sure to rename the Name to Settings.settings.
5. In the Settings editor, which appears now, add a value and try to save the settings.

Expected Behavior: Settings file should be written, settings designer code be generated. Actual Behavior:

Exception: ‘An error occurred creating the configuration section handler for userSettings/VbWinForms5EventTest.Settings: Could not load file or assembly ‘System.Configuration.ConfigurationManager, Version=5.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51’ or one of its dependencies. The system cannot find the file specified.’

User Impact: Interactively using the settings designer in a .NET 5 VB WinForms App is not possible.

Stack Trace:

   at System.Configuration.BaseConfigurationRecord.FindAndEnsureFactoryRecord(String configKey, Boolean& isRootDeclaredHere)
   at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject)
   at Microsoft.VisualStudio.Shell.Design.Serialization.ConfigurationHelperService.GetConfigSection(Configuration config, String sectionName, Boolean isUserScoped, Boolean declare)
   at Microsoft.VisualStudio.Shell.Design.Serialization.ConfigurationHelperService.ReadSettings(ExeConfigurationFileMap fileMap, ConfigurationUserLevel userLevel, DocData appConfigDocData, String sectionName, Boolean isUserScoped, SettingsPropertyCollection settings)
   at Microsoft.VisualStudio.Editors.SettingsDesigner.AppConfigSerializer.SynchronizeUserConfig(String SectionName, IVsHierarchy Hierarchy, ConfigurationHelperService ConfigHelperService, Dictionary`2 SettingsTheDesignerKnownsAbout, DocData AppConfigDocData) in D:\Git\project-system\src\Microsoft.VisualStudio.Editors\SettingsDesigner\AppConfigSerializer.vb:line 402
   at Microsoft.VisualStudio.Editors.SettingsDesigner.AppConfigSerializer.SynchronizeUserConfig(String SectionName, IVsHierarchy Hierarchy, ConfigurationHelperService ConfigHelperService, DesignTimeSettings Settings, DocData AppConfigDocData) in D:\Git\project-system\src\Microsoft.VisualStudio.Editors\SettingsDesigner\AppConfigSerializer.vb:line 347
   at Microsoft.VisualStudio.Editors.SettingsDesigner.AppConfigSerializer.Serialize(DesignTimeSettings Settings, SettingsTypeCache typeCache, SettingsValueCache valueCache, String SectionName, DocData AppConfigDocData, IVsHierarchy Hierarchy, Boolean ShouldSynchronizeUserConfig) in D:\Git\project-system\src\Microsoft.VisualStudio.Editors\SettingsDesigner\AppConfigSerializer.vb:line 320

[melytc]

Change missing here is removing the system.diagnostics content from the VB AppConfiguration template. Closing this in favor of #7448 which needs the same change.

[ocallesp]

The PR https://devdiv.visualstudio.com/DevDiv/_git/VS/pullrequest/403807 should handle the issue in system.diagnostics