IntelliSense in Razor files (.cshtml) stopped working

Question

Intellisense does not work in razor files:

In my web.conifg file (in the Views folder) is apparently correct:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <configSections>
        <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
            <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
            <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
        </sectionGroup>
    </configSections>

    <system.web.webPages.razor>
        <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <pages pageBaseType="System.Web.Mvc.WebViewPage">
            <namespaces>
                <add namespace="System.Web.Mvc" />
                <add namespace="System.Web.Mvc.Ajax" />
                <add namespace="System.Web.Mvc.Html" />
                <add namespace="System.Web.Routing" />
                <add namespace="System.Web.Optimization" />

                <add namespace="MvcSiteMapProvider.Web.Html" />
                <add namespace="MvcSiteMapProvider.Web.Html.Models" />

                <add namespace="DevTrends.MvcDonutCaching" />
            </namespaces>
        </pages>
    </system.web.webPages.razor>

    <appSettings>
        <add key="webpages:Enabled" value="false" />
    </appSettings>

    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <handlers>
            <remove name="BlockViewHandler" />
            <add name="BlockViewHandler" path="*" verb="*" preCondition="integratedMode" type="System.Web.HttpNotFoundHandler" />
        </handlers>
    </system.webServer>
</configuration>

Answer 1

This is what worked for me after IntelliSense suddenly began to bug out and stopped colouring C# code correctly in between the HTML tags in my views:

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Just delete the contents of the folder at %LOCALAPPDATA%\Microsoft\VisualStudio\14.0\ComponentModelCache

If you're using VS 2019, the version folder is named 16.0_<hash>.

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As an additional step, you can optionally run the command DevEnv.exe /setup in Developer Command Prompt for VS (as an Administrator) if the above step doesn't resolve the issue.