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Sentry .NET SDK

Opinionated wizard that scans your .NET project and guides you through complete Sentry setup: error monitoring, distributed tracing, profiling, structured logging, and cron monitoring across all major .NET frameworks.

Invoke This Skill When

User asks to "add Sentry to .NET", "set up Sentry in C#", or "install Sentry for ASP.NET Core"
User wants error monitoring, tracing, profiling, logging, or crons for a .NET app
User mentions SentrySdk.Init, UseSentry, Sentry.AspNetCore, or Sentry.Maui
User wants to capture unhandled exceptions in WPF, WinForms, MAUI, or Azure Functions
User asks about SentryOptions, BeforeSend, TracesSampleRate, or symbol upload

Note: SDK version and APIs below reflect Sentry NuGet packages ≥6.1.0. Always verify against docs.sentry.io/platforms/dotnet/ before implementing.

Phase 1: Detect

Run these commands to understand the project before making any recommendations:

# Detect framework type — find all .csproj files
find . -name "*.csproj" | head -20

# Detect framework targets
grep -r "TargetFramework\|Project Sdk" --include="*.csproj" .

# Check for existing Sentry packages
grep -r "Sentry" --include="*.csproj" . | grep "PackageReference"

# Check startup files
ls Program.cs src/Program.cs App.xaml.cs MauiProgram.cs 2>/dev/null

# Check for appsettings
ls appsettings.json src/appsettings.json 2>/dev/null

# Check for logging libraries
grep -r "Serilog\|NLog\|log4net" --include="*.csproj" .

# Check for companion frontend
ls ../frontend ../client ../web 2>/dev/null
cat ../package.json 2>/dev/null | grep -E '"next"|"react"|"vue"' | head -3

What to determine:

Question	Impact
Framework type?	Determines correct package and init pattern
.NET version?	.NET 8+ recommended; .NET Framework 4.6.2+ supported
Sentry already installed?	Skip install, go to feature config
Logging library (Serilog, NLog)?	Recommend matching Sentry sink/target
Async/hosted app (ASP.NET Core)?	`UseSentry()` on `WebHost`; no `IsGlobalModeEnabled` needed
Desktop app (WPF, WinForms, WinUI)?	Must set `IsGlobalModeEnabled = true`
Serverless (Azure Functions, Lambda)?	Must set `FlushOnCompletedRequest = true`
Frontend directory found?	Trigger Phase 4 cross-link

Framework → Package mapping:

Detected	Package to install
`Sdk="Microsoft.NET.Sdk.Web"` (ASP.NET Core)	`Sentry.AspNetCore`
`App.xaml.cs` with `Application` base	`Sentry` (WPF)
`[STAThread]` in `Program.cs`	`Sentry` (WinForms)
`MauiProgram.cs`	`Sentry.Maui`
`WebAssemblyHostBuilder`	`Sentry.AspNetCore.Blazor.WebAssembly`
`FunctionsStartup`	`Sentry.Extensions.Logging` + `Sentry.OpenTelemetry`
`HttpApplication` / `Global.asax`	`Sentry.AspNet`
Generic host / Worker Service	`Sentry.Extensions.Logging`

Phase 2: Recommend

Present a concrete recommendation based on what you found. Lead with a proposal — don't ask open-ended questions.

Recommended (core coverage):

✅ Error Monitoring — always; captures unhandled exceptions, structured captures, scope enrichment
✅ Tracing — always for ASP.NET Core and hosted apps; auto-instruments HTTP requests and EF Core queries
✅ Logging — recommended for all apps; routes ILogger / Serilog / NLog entries to Sentry as breadcrumbs and events

Optional (enhanced observability):

⚡ Profiling — CPU profiling; recommend for performance-critical services running on .NET 6+
⚡ Crons — detect missed/failed scheduled jobs; recommend when Hangfire, Quartz.NET, or scheduled endpoints detected

Recommendation logic:

Feature	Recommend when...
Error Monitoring	Always — non-negotiable baseline
Tracing	Always for ASP.NET Core — request traces, EF Core spans, HttpClient spans are high-value
Logging	App uses `ILogger<T>`, Serilog, NLog, or log4net
Profiling	Performance-critical service on .NET 6+
Crons	App uses Hangfire, Quartz.NET, or scheduled Azure Functions

Propose: "I recommend setting up Error Monitoring + Tracing + Logging. Want me to also add Profiling or Crons?"

Phase 3: Guide

Option 1: Wizard (Recommended)

You need to run this yourself — the wizard opens a browser for login and requires interactive input that the agent can't handle. Copy-paste into your terminal:
npx @sentry/wizard@latest -i dotnet
It handles login, org/project selection, DSN configuration, and MSBuild symbol upload setup for readable stack traces in production.

Once it finishes, come back and skip to Verification.

If the user skips the wizard, proceed with Option 2 (Manual Setup) below.

Option 2: Manual Setup

Install the right package

# ASP.NET Core
dotnet add package Sentry.AspNetCore -v 6.1.0

# WPF or WinForms or Console
dotnet add package Sentry -v 6.1.0

# .NET MAUI
dotnet add package Sentry.Maui -v 6.1.0

# Blazor WebAssembly
dotnet add package Sentry.AspNetCore.Blazor.WebAssembly -v 6.1.0

# Azure Functions (Isolated Worker)
dotnet add package Sentry.Extensions.Logging -v 6.1.0
dotnet add package Sentry.OpenTelemetry -v 6.1.0

# Classic ASP.NET (System.Web / .NET Framework)
dotnet add package Sentry.AspNet -v 6.1.0

ASP.NET Core — `Program.cs`

var builder = WebApplication.CreateBuilder(args);

builder.WebHost.UseSentry(options =>
{
    options.Dsn = Environment.GetEnvironmentVariable("SENTRY_DSN")
                  ?? "___YOUR_DSN___";
    options.Debug = true;                         // disable in production
    options.SendDefaultPii = true;                // captures user IP, name, email
    options.MaxRequestBodySize = RequestSize.Always;
    options.MinimumBreadcrumbLevel = LogLevel.Debug;
    options.MinimumEventLevel = LogLevel.Warning;
    options.TracesSampleRate = 1.0;               // tune to 0.1–0.2 in production
    options.SetBeforeSend((@event, hint) =>
    {
        @event.ServerName = null;                 // scrub hostname from events
        return @event;
    });
});

var app = builder.Build();
app.Run();

appsettings.json (alternative configuration):

{
  "Sentry": {
    "Dsn": "___YOUR_DSN___",
    "SendDefaultPii": true,
    "MaxRequestBodySize": "Always",
    "MinimumBreadcrumbLevel": "Debug",
    "MinimumEventLevel": "Warning",
    "AttachStacktrace": true,
    "Debug": true,
    "TracesSampleRate": 1.0,
    "Environment": "production",
    "Release": "my-app@1.0.0"
  }
}

Environment variables (double underscore as separator):

export Sentry__Dsn="https://examplePublicKey@o0.ingest.sentry.io/0"
export Sentry__TracesSampleRate="0.1"
export Sentry__Environment="staging"

WPF — `App.xaml.cs`

⚠️ Critical: Initialize in the constructor, NOT in OnStartup(). The constructor fires earlier, catching more failure modes.

using System.Windows;
using Sentry;

public partial class App : Application
{
    public App()
    {
        SentrySdk.Init(options =>
        {
            options.Dsn = "___YOUR_DSN___";
            options.Debug = true;
            options.SendDefaultPii = true;
            options.TracesSampleRate = 1.0;
            options.IsGlobalModeEnabled = true;   // required for all desktop apps
        });

        // Capture WPF UI-thread exceptions before WPF's crash dialog appears
        DispatcherUnhandledException += App_DispatcherUnhandledException;
    }

    private void App_DispatcherUnhandledException(
        object sender,
        System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)
    {
        SentrySdk.CaptureException(e.Exception);
        // Set e.Handled = true to prevent crash dialog and keep app running
    }
}

WinForms — `Program.cs`

using System;
using System.Windows.Forms;
using Sentry;

static class Program
{
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);

        // Required: allows Sentry to see unhandled WinForms exceptions
        Application.SetUnhandledExceptionMode(UnhandledExceptionMode.ThrowException);

        using (SentrySdk.Init(new SentryOptions
        {
            Dsn = "___YOUR_DSN___",
            Debug = true,
            TracesSampleRate = 1.0,
            IsGlobalModeEnabled = true,           // required for desktop apps
        }))
        {
            Application.Run(new MainForm());
        } // Disposing flushes all pending events
    }
}

.NET MAUI — `MauiProgram.cs`

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiApp<App>()
            .UseSentry(options =>
            {
                options.Dsn = "___YOUR_DSN___";
                options.Debug = true;
                options.SendDefaultPii = true;
                options.TracesSampleRate = 1.0;
                // MAUI-specific: opt-in breadcrumbs (off by default — PII risk)
                options.IncludeTextInBreadcrumbs = false;
                options.IncludeTitleInBreadcrumbs = false;
                options.IncludeBackgroundingStateInBreadcrumbs = false;
            });

        return builder.Build();
    }
}

Blazor WebAssembly — `Program.cs`

var builder = WebAssemblyHostBuilder.CreateDefault(args);

builder.UseSentry(options =>
{
    options.Dsn = "___YOUR_DSN___";
    options.Debug = true;
    options.SendDefaultPii = true;
    options.TracesSampleRate = 0.1;
});

// Hook logging pipeline without re-initializing the SDK
builder.Logging.AddSentry(o => o.InitializeSdk = false);

await builder.Build().RunAsync();

Azure Functions (Isolated Worker) — `Program.cs`

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using OpenTelemetry.Trace;
using Sentry.OpenTelemetry;

var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults()
    .ConfigureServices(services =>
    {
        services.AddOpenTelemetry().WithTracing(builder =>
        {
            builder
                .AddSentry()                        // route OTel spans to Sentry
                .AddHttpClientInstrumentation();    // capture outgoing HTTP
        });
    })
    .ConfigureLogging(logging =>
    {
        logging.AddSentry(options =>
        {
            options.Dsn = "___YOUR_DSN___";
            options.Debug = true;
            options.TracesSampleRate = 1.0;
            options.UseOpenTelemetry();                     // let OTel drive tracing
            options.DisableSentryHttpMessageHandler = true; // prevent duplicate HTTP spans
        });
    })
    .Build();

await host.RunAsync();

AWS Lambda — `LambdaEntryPoint.cs`

public class LambdaEntryPoint : APIGatewayProxyFunction
{
    protected override void Init(IWebHostBuilder builder)
    {
        builder
            .UseSentry(options =>
            {
                options.Dsn = "___YOUR_DSN___";
                options.TracesSampleRate = 1.0;
                options.FlushOnCompletedRequest = true; // REQUIRED for Lambda
            })
            .UseStartup<Startup>();
    }
}

Classic ASP.NET — `Global.asax.cs`

public class MvcApplication : HttpApplication
{
    private IDisposable _sentry;

    protected void Application_Start()
    {
        _sentry = SentrySdk.Init(options =>
        {
            options.Dsn = "___YOUR_DSN___";
            options.TracesSampleRate = 1.0;
            options.AddEntityFramework(); // EF6 query breadcrumbs
            options.AddAspNet();          // Classic ASP.NET integration
        });
    }

    protected void Application_Error() => Server.CaptureLastError();

    protected void Application_BeginRequest() => Context.StartSentryTransaction();
    protected void Application_EndRequest() => Context.FinishSentryTransaction();

    protected void Application_End() => _sentry?.Dispose();
}

Symbol Upload (Readable Stack Traces)

Without debug symbols, stack traces show only method names — no file names or line numbers. Upload PDB files to unlock full source context.

Step 1: Create a Sentry auth token

Go to sentry.io/settings/auth-tokens/ and create a token with project:releases and org:read scopes.

Step 2: Add MSBuild properties to .csproj or Directory.Build.props:

<PropertyGroup Condition="'$(Configuration)' == 'Release'">
  <SentryOrg>___ORG_SLUG___</SentryOrg>
  <SentryProject>___PROJECT_SLUG___</SentryProject>
  <SentryUploadSymbols>true</SentryUploadSymbols>
  <SentryUploadSources>true</SentryUploadSources>
  <SentryCreateRelease>true</SentryCreateRelease>
  <SentrySetCommits>true</SentrySetCommits>
</PropertyGroup>

Step 3: Set SENTRY_AUTH_TOKEN in CI:

# GitHub Actions
- name: Build & upload symbols
  run: dotnet build -c Release
  env:
    SENTRY_AUTH_TOKEN: ${{ secrets.SENTRY_AUTH_TOKEN }}

For Each Agreed Feature

Load the corresponding reference file and follow its steps:

Feature	Reference file	Load when...
Error Monitoring	`references/error-monitoring.md`	Always — `CaptureException`, scopes, enrichment, filtering
Tracing	`references/tracing.md`	Server apps, distributed tracing, EF Core spans, custom instrumentation
Profiling	`references/profiling.md`	Performance-critical apps on .NET 6+
Logging	`references/logging.md`	`ILogger<T>`, Serilog, NLog, log4net integration
Crons	`references/crons.md`	Hangfire, Quartz.NET, or scheduled function monitoring

For each feature: read the reference file, follow its steps exactly, and verify before moving on.

Verification

After wizard or manual setup, add a test throw and remove it after verifying:

// ASP.NET Core: add a temporary endpoint
app.MapGet("/sentry-test", () =>
{
    throw new Exception("Sentry test error — delete me");
});

// Or capture explicitly anywhere
SentrySdk.CaptureException(new Exception("Sentry test error — delete me"));

Then check your Sentry Issues dashboard — the error should appear within ~30 seconds.

Verification checklist:

Check	How
Exceptions captured	Throw a test exception, verify in Sentry Issues
Stack traces readable	Check that file names and line numbers appear
Tracing active	Check Performance tab for transactions
Logging wired	Log an error via `ILogger`, check it appears as Sentry breadcrumb
Symbol upload working	Stack trace shows `Controllers/HomeController.cs:42` not `<unknown>`

Config Reference

Core `SentryOptions`

Option	Type	Default	Env Var	Notes
`Dsn`	`string`	—	`SENTRY_DSN`	Required. SDK disabled if unset.
`Debug`	`bool`	`false`	—	SDK diagnostic output. Disable in production.
`DiagnosticLevel`	`SentryLevel`	`Debug`	—	`Debug`, `Info`, `Warning`, `Error`, `Fatal`
`Release`	`string`	auto	`SENTRY_RELEASE`	Auto-detected from assembly version + git SHA
`Environment`	`string`	`"production"`	`SENTRY_ENVIRONMENT`	`"debug"` when debugger attached
`Dist`	`string`	—	—	Build variant. Max 64 chars.
`SampleRate`	`float`	`1.0`	—	Error event sampling rate 0.0–1.0
`TracesSampleRate`	`double`	`0.0`	—	Transaction sampling. Must be `> 0` to enable.
`TracesSampler`	`Func<SamplingContext, double>`	—	—	Per-transaction dynamic sampler; overrides `TracesSampleRate`
`ProfilesSampleRate`	`double`	`0.0`	—	Fraction of traced transactions to profile. Requires `Sentry.Profiling`.
`SendDefaultPii`	`bool`	`false`	—	Include user IP, name, email
`AttachStacktrace`	`bool`	`true`	—	Attach stack trace to all messages
`MaxBreadcrumbs`	`int`	`100`	—	Max breadcrumbs stored per event
`IsGlobalModeEnabled`	`bool`	`false`*	—	Auto-`true` for MAUI, Blazor WASM. Must* be `true` for WPF, WinForms, Console.
`AutoSessionTracking`	`bool`	`false`*	—	*Auto-`true` for MAUI. Enable for Release Health.
`CaptureFailedRequests`	`bool`	`true`	—	Auto-capture HTTP client errors
`CacheDirectoryPath`	`string`	—	—	Offline event caching directory
`ShutdownTimeout`	`TimeSpan`	—	—	Max wait for event flush on shutdown
`HttpProxy`	`string`	—	—	Proxy URL for Sentry requests
`EnableBackpressureHandling`	`bool`	`true`	—	Auto-reduce sample rates on delivery failures

ASP.NET Core Extended Options (`SentryAspNetCoreOptions`)

Option	Type	Default	Notes
`MaxRequestBodySize`	`RequestSize`	`None`	`None`, `Small` (~4 KB), `Medium` (~10 KB), `Always`
`MinimumBreadcrumbLevel`	`LogLevel`	`Information`	Min log level for breadcrumbs
`MinimumEventLevel`	`LogLevel`	`Error`	Min log level to send as Sentry event
`CaptureBlockingCalls`	`bool`	`false`	Detect `.Wait()` / `.Result` threadpool starvation
`FlushOnCompletedRequest`	`bool`	`false`	Required for Lambda / serverless
`IncludeActivityData`	`bool`	`false`	Capture `System.Diagnostics.Activity` values

MAUI Extended Options (`SentryMauiOptions`)

Option	Type	Default	Notes
`IncludeTextInBreadcrumbs`	`bool`	`false`	Text from `Button`, `Label`, `Entry` elements. ⚠️ PII risk.
`IncludeTitleInBreadcrumbs`	`bool`	`false`	Titles from `Window`, `Page` elements. ⚠️ PII risk.
`IncludeBackgroundingStateInBreadcrumbs`	`bool`	`false`	`Window.Backgrounding` event state. ⚠️ PII risk.

Environment Variables

Variable	Purpose
`SENTRY_DSN`	Project DSN
`SENTRY_RELEASE`	App version (e.g. `my-app@1.2.3`)
`SENTRY_ENVIRONMENT`	Deployment environment name
`SENTRY_AUTH_TOKEN`	MSBuild / `sentry-cli` symbol upload auth token

ASP.NET Core: use double underscore __ as hierarchy separator:

export Sentry__Dsn="https://..."
export Sentry__TracesSampleRate="0.1"

MSBuild Symbol Upload Properties

Property	Type	Default	Description
`SentryOrg`	`string`	—	Sentry organization slug
`SentryProject`	`string`	—	Sentry project slug
`SentryUploadSymbols`	`bool`	`false`	Upload PDB files for line numbers in stack traces
`SentryUploadSources`	`bool`	`false`	Upload source files for source context
`SentryCreateRelease`	`bool`	`false`	Auto-create a Sentry release during build
`SentrySetCommits`	`bool`	`false`	Associate git commits with the release
`SentryUrl`	`string`	—	Self-hosted Sentry URL

Phase 4: Cross-Link

After completing .NET setup, check for companion frontend projects:

# Check for frontend in adjacent directories
ls ../frontend ../client ../web ../app 2>/dev/null

# Check for JavaScript framework indicators
cat ../package.json 2>/dev/null | grep -E '"next"|"react"|"vue"|"nuxt"' | head -3

If a frontend is found, suggest the matching SDK skill:

Frontend detected	Suggest skill
Next.js (`"next"` in `package.json`)	`sentry-nextjs-sdk`
React SPA (`"react"` without `"next"`)	`@sentry/react` — see docs.sentry.io/platforms/javascript/guides/react/
Vue.js	`@sentry/vue` — see docs.sentry.io/platforms/javascript/guides/vue/
Nuxt	`@sentry/nuxt` — see docs.sentry.io/platforms/javascript/guides/nuxt/

Connecting frontend and backend with the same Sentry project enables distributed tracing — a single trace view spanning browser, .NET server, and any downstream APIs.

Troubleshooting

Issue	Cause	Solution
Events not appearing	DSN misconfigured	Set `Debug = true` and check console output for SDK diagnostic messages
Stack traces show no file/line	PDB files not uploaded	Add `SentryUploadSymbols=true` to `.csproj`; set `SENTRY_AUTH_TOKEN` in CI
WPF/WinForms exceptions missing	`IsGlobalModeEnabled` not set	Set `options.IsGlobalModeEnabled = true` in `SentrySdk.Init()`
Lambda/serverless events lost	Container freezes before flush	Set `options.FlushOnCompletedRequest = true`
WPF UI-thread exceptions missing	`DispatcherUnhandledException` not wired	Register `App.DispatcherUnhandledException` in constructor (not `OnStartup`)
Duplicate HTTP spans in Azure Functions	Both Sentry and OTel instrument HTTP	Set `options.DisableSentryHttpMessageHandler = true`
`TracesSampleRate` has no effect	Rate is `0.0` (default)	Set `TracesSampleRate > 0` to enable tracing
`appsettings.json` values ignored	Config key format wrong	Use flat key `"Sentry:Dsn"` or env var `Sentry__Dsn` (double underscore)
`BeforeSend` drops all events	Hook returns `null` unconditionally	Verify your filter logic; return `null` only for events you want to drop
MAUI native crashes not captured	Wrong package	Confirm `Sentry.Maui` is installed (not just `Sentry`)

sentry-dotnet-sdk