Application Insight Snapshot Debugger: Snapshots are not being pushed from a .NET Full Framework Site

Question

I created a brand new Web Application, .NET Full Framework 4.7.2, added Application Insights Snapshot Collector but snapshots are not being pushed to the server.

I'm not even getting the Don't see the snapshot? troubleshoot link they mention here.

I tested my integration key using a .NET Core app and it works as expected, and I'm even getting logs at %TEMP%\Dumps64 as they mention in that document.

I don't see any activity in the %TEMP% folder when I use the .NET Framework app. Exceptions are being pushed to Application Insights, so the integration key is valid and the exceptions are being trapped.

These are the packages I added:

<package id="Microsoft.ApplicationInsights" version="2.9.1" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.Agent.Intercept" version="2.4.0" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.DependencyCollector" version="2.9.1" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.PerfCounterCollector" version="2.9.1" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.SnapshotCollector" version="1.3.3" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.TraceListener" version="2.9.1" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.Web" version="2.9.1" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.WindowsServer" version="2.9.1" targetFramework="net472" />
<package id="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel" version="2.9.1" targetFramework="net472" />

And this is how my ApplicationInsights.config looks like:

<?xml version="1.0" encoding="utf-8"?>
<ApplicationInsights xmlns="http://schemas.microsoft.com/ApplicationInsights/2013/Settings">
  <InstrumentationKey>[MY INTEGRATION KEY IS HERE]</InstrumentationKey>
  <TelemetryInitializers>
    <Add Type="Microsoft.ApplicationInsights.DependencyCollector.HttpDependenciesParsingTelemetryInitializer, Microsoft.AI.DependencyCollector"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.AzureRoleEnvironmentTelemetryInitializer, Microsoft.AI.WindowsServer"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.AzureWebAppRoleEnvironmentTelemetryInitializer, Microsoft.AI.WindowsServer"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.BuildInfoConfigComponentVersionTelemetryInitializer, Microsoft.AI.WindowsServer"/>
    <Add Type="Microsoft.ApplicationInsights.Web.WebTestTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.SyntheticUserAgentTelemetryInitializer, Microsoft.AI.Web">
      <!-- Extended list of bots:
            search|spider|crawl|Bot|Monitor|BrowserMob|BingPreview|PagePeeker|WebThumb|URL2PNG|ZooShot|GomezA|Google SketchUp|Read Later|KTXN|KHTE|Keynote|Pingdom|AlwaysOn|zao|borg|oegp|silk|Xenu|zeal|NING|htdig|lycos|slurp|teoma|voila|yahoo|Sogou|CiBra|Nutch|Java|JNLP|Daumoa|Genieo|ichiro|larbin|pompos|Scrapy|snappy|speedy|vortex|favicon|indexer|Riddler|scooter|scraper|scrubby|WhatWeb|WinHTTP|voyager|archiver|Icarus6j|mogimogi|Netvibes|altavista|charlotte|findlinks|Retreiver|TLSProber|WordPress|wsr-agent|http client|Python-urllib|AppEngine-Google|semanticdiscovery|facebookexternalhit|web/snippet|Google-HTTP-Java-Client-->
      <Filters>search|spider|crawl|Bot|Monitor|AlwaysOn</Filters>
    </Add>
    <Add Type="Microsoft.ApplicationInsights.Web.ClientIpHeaderTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.OperationNameTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.OperationCorrelationTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.UserTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.AuthenticatedUserIdTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.AccountIdTelemetryInitializer, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.SessionTelemetryInitializer, Microsoft.AI.Web"/>
  </TelemetryInitializers>
  <!-- 
    Learn more about Application Insights configuration with ApplicationInsights.config here: 
    http://go.microsoft.com/fwlink/?LinkID=513840

    Note: If not present, please add <InstrumentationKey>Your Key</InstrumentationKey> to the top of this file.
  -->
  <TelemetrySinks>
    <Add Name="default">
      <TelemetryProcessors>
        <Add Type="Microsoft.ApplicationInsights.Extensibility.PerfCounterCollector.QuickPulse.QuickPulseTelemetryProcessor, Microsoft.AI.PerfCounterCollector"/>
        <Add Type="Microsoft.ApplicationInsights.SnapshotCollector.SnapshotCollectorTelemetryProcessor, Microsoft.ApplicationInsights.SnapshotCollector">
          <!-- The default is true, but you can disable Snapshot Debugging by setting it to false -->
          <IsEnabled>true</IsEnabled>
          <!-- Snapshot Debugging is usually disabled in developer mode, but you can enable it by setting this to true. -->
          <!-- DeveloperMode is a property on the active TelemetryChannel. -->
          <IsEnabledInDeveloperMode>true</IsEnabledInDeveloperMode>
        </Add>
        <Add Type="Microsoft.ApplicationInsights.Extensibility.AutocollectedMetricsExtractor, Microsoft.ApplicationInsights"/>
        <Add Type="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel.AdaptiveSamplingTelemetryProcessor, Microsoft.AI.ServerTelemetryChannel">
          <MaxTelemetryItemsPerSecond>5</MaxTelemetryItemsPerSecond>
          <ExcludedTypes>Event</ExcludedTypes>
        </Add>
        <Add Type="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel.AdaptiveSamplingTelemetryProcessor, Microsoft.AI.ServerTelemetryChannel">
          <MaxTelemetryItemsPerSecond>5</MaxTelemetryItemsPerSecond>
          <IncludedTypes>Event</IncludedTypes>
        </Add>
      </TelemetryProcessors>
      <TelemetryChannel Type="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel.ServerTelemetryChannel, Microsoft.AI.ServerTelemetryChannel"/>
    </Add>
  </TelemetrySinks>
  <TelemetryModules>
    <Add Type="Microsoft.ApplicationInsights.DependencyCollector.DependencyTrackingTelemetryModule, Microsoft.AI.DependencyCollector">
      <ExcludeComponentCorrelationHttpHeadersOnDomains>
        <!-- 
        Requests to the following hostnames will not be modified by adding correlation headers.         
        Add entries here to exclude additional hostnames.
        NOTE: this configuration will be lost upon NuGet upgrade.
        -->
        <Add>core.windows.net</Add>
        <Add>core.chinacloudapi.cn</Add>
        <Add>core.cloudapi.de</Add>
        <Add>core.usgovcloudapi.net</Add>
      </ExcludeComponentCorrelationHttpHeadersOnDomains>
      <IncludeDiagnosticSourceActivities>
        <Add>Microsoft.Azure.EventHubs</Add>
        <Add>Microsoft.Azure.ServiceBus</Add>
      </IncludeDiagnosticSourceActivities>
    </Add>
    <Add Type="Microsoft.ApplicationInsights.Extensibility.PerfCounterCollector.PerformanceCollectorModule, Microsoft.AI.PerfCounterCollector">
      <!--
      Use the following syntax here to collect additional performance counters:

      <Counters>
        <Add PerformanceCounter="\Process(??APP_WIN32_PROC??)\Handle Count" ReportAs="Process handle count" />
        ...
      </Counters>

      PerformanceCounter must be either \CategoryName(InstanceName)\CounterName or \CategoryName\CounterName

      NOTE: performance counters configuration will be lost upon NuGet upgrade.

      The following placeholders are supported as InstanceName:
        ??APP_WIN32_PROC?? - instance name of the application process  for Win32 counters.
        ??APP_W3SVC_PROC?? - instance name of the application IIS worker process for IIS/ASP.NET counters.
        ??APP_CLR_PROC?? - instance name of the application CLR process for .NET counters.
      -->
    </Add>
    <Add Type="Microsoft.ApplicationInsights.Extensibility.PerfCounterCollector.QuickPulse.QuickPulseTelemetryModule, Microsoft.AI.PerfCounterCollector"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.AppServicesHeartbeatTelemetryModule, Microsoft.AI.WindowsServer"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.AzureInstanceMetadataTelemetryModule, Microsoft.AI.WindowsServer">
      <!--
      Remove individual fields collected here by adding them to the ApplicationInsighs.HeartbeatProvider 
      with the following syntax:

      <Add Type="Microsoft.ApplicationInsights.Extensibility.Implementation.Tracing.DiagnosticsTelemetryModule, Microsoft.ApplicationInsights">
        <ExcludedHeartbeatProperties>
          <Add>osType</Add>
          <Add>location</Add>
          <Add>name</Add>
          <Add>offer</Add>
          <Add>platformFaultDomain</Add>
          <Add>platformUpdateDomain</Add>
          <Add>publisher</Add>
          <Add>sku</Add>
          <Add>version</Add>
          <Add>vmId</Add>
          <Add>vmSize</Add>
          <Add>subscriptionId</Add>
          <Add>resourceGroupName</Add>
          <Add>placementGroupId</Add>
          <Add>tags</Add>
          <Add>vmScaleSetName</Add>
        </ExcludedHeartbeatProperties>
      </Add>

      NOTE: exclusions will be lost upon upgrade.
      -->
    </Add>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.DeveloperModeWithDebuggerAttachedTelemetryModule, Microsoft.AI.WindowsServer"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.UnhandledExceptionTelemetryModule, Microsoft.AI.WindowsServer"/>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.UnobservedExceptionTelemetryModule, Microsoft.AI.WindowsServer">
      <!--</Add>
    <Add Type="Microsoft.ApplicationInsights.WindowsServer.FirstChanceExceptionStatisticsTelemetryModule, Microsoft.AI.WindowsServer">-->
    </Add>
    <Add Type="Microsoft.ApplicationInsights.Web.RequestTrackingTelemetryModule, Microsoft.AI.Web">
      <Handlers>
        <!-- 
        Add entries here to filter out additional handlers: 

        NOTE: handler configuration will be lost upon NuGet upgrade.
        -->
        <Add>Microsoft.VisualStudio.Web.PageInspector.Runtime.Tracing.RequestDataHttpHandler</Add>
        <Add>System.Web.StaticFileHandler</Add>
        <Add>System.Web.Handlers.AssemblyResourceLoader</Add>
        <Add>System.Web.Optimization.BundleHandler</Add>
        <Add>System.Web.Script.Services.ScriptHandlerFactory</Add>
        <Add>System.Web.Handlers.TraceHandler</Add>
        <Add>System.Web.Services.Discovery.DiscoveryRequestHandler</Add>
        <Add>System.Web.HttpDebugHandler</Add>
      </Handlers>
    </Add>
    <Add Type="Microsoft.ApplicationInsights.Web.ExceptionTrackingTelemetryModule, Microsoft.AI.Web"/>
    <Add Type="Microsoft.ApplicationInsights.Web.AspNetDiagnosticTelemetryModule, Microsoft.AI.Web"/>
  </TelemetryModules>
  <ApplicationIdProvider Type="Microsoft.ApplicationInsights.Extensibility.Implementation.ApplicationId.ApplicationInsightsApplicationIdProvider, Microsoft.ApplicationInsights"/>

<!-- 
    Learn more about Application Insights configuration with ApplicationInsights.config here: 
    http://go.microsoft.com/fwlink/?LinkID=513840

    Note: If not present, please add <InstrumentationKey>Your Key</InstrumentationKey> to the top of this file.
  -->
    <TelemetryProcessors>
        <Add Type="Microsoft.ApplicationInsights.SnapshotCollector.SnapshotCollectorTelemetryProcessor, Microsoft.ApplicationInsights.SnapshotCollector">
            <!-- Snapshot Debugging is usually disabled when debugging in Visual Studio, but you can enable it by setting this to true. -->
            <IsEnabled>true</IsEnabled>
            <!-- Snapshot Debugging is usually disabled in developer mode, but you can enable it by setting this to true. -->
            <!-- DeveloperMode is a property on the active TelemetryChannel. -->
            <IsEnabledInDeveloperMode>true</IsEnabledInDeveloperMode>
            <!-- How many times we need to see an exception before we ask for snapshots. -->
            <ThresholdForSnapshotting>1</ThresholdForSnapshotting>
            <!-- Other properties are documented at https://aka.ms/pnv0qt -->
        </Add>
    </TelemetryProcessors>
</ApplicationInsights>

What am I missing?

Answer 1

Answered this originally in GitHub issue.

So I've just spent almost a day trying to make snapshot debugger work in a legacy ASP.NET application and now it finally works! While there's no guarantee that the issue I've encountered is the same as yours was, I believe it is quite possible, because the symptoms I experienced were basically the same.

TL;DR: it is <assemblyBinding>.

Problem

Application Insights probably tries to be resilient to failures by preferring to (silently?) ignore them.

And that is what it does to SnapshotCollectorTelemetryProcessor. It simply silently skips it if it fails to load and proceeds happily without it. You can verify this by entering any garbage instead of Microsoft.ApplicationInsights.SnapshotCollector.SnapshotCollectorTelemetryProcessor, Microsoft.ApplicationInsights.SnapshotCollector as Type attribute value in ApplicationInsights.config.

And if you check TelemetryConfiguration.Active.DefaultTelemetrySink.TelemetryProcessors, it will simply miss those it failed to load.

A sure way to verify that problem is with assembly loading, just add this line somewhere in startup code:

var _ = typeof(SnapshotCollectorTelemetryProcessor);

That should trigger the error.

AFAIK, unlike with class library projects, Web.config in ASP.NET applications cannot benefit from <AutoGenerateBindingRedirects>, while NuGet package manager in VS won't do it either once you move to PackageReference (or to "new csproj with globs" like I did). So you have to maintain it somewhat manually.

"Fix"

As of today, assuming you have these reference versions in your csproj file,

<PackageReference Include="Microsoft.ApplicationInsights.SnapshotCollector" Version="1.3.7" />
<PackageReference Include="Microsoft.ApplicationInsights.Web" Version="2.14.0" />

you will probably need at least these redirects in Web.config

<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  <dependentAssembly>
    <assemblyIdentity name="Microsoft.ApplicationInsights" publicKeyToken="31bf3856ad364e35" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-2.14.0.17971" newVersion="2.14.0.17971" />
  </dependentAssembly>
  <dependentAssembly>
    <assemblyIdentity name="Microsoft.ApplicationInsights.SnapshotCollector" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-1.3.7.0" newVersion="1.3.7.0" />
  </dependentAssembly>
  <dependentAssembly>
    <assemblyIdentity name="System.Diagnostics.DiagnosticSource" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.0.4.0" newVersion="4.0.4.0" />
  </dependentAssembly>
</assemblyBinding>

After adding those, I could see the SnapshotUploader directory created on disk and soon after simulating exceptions, some snapshots in the portal.

Extra quirks

As described above, the configuration by default is wrongly added to the root in ApplicationInsights.config and not under default sink.

Additionally, that sink configuration created by Microsoft.ApplicationInsights.Web contains duplicate entries for AdaptiveSamplingTelemetryProcessor, which will probably cause much less telemetry to be sampled than expected in some cases.