sentry-dotnet-sdk

name	sentry-dotnet-sdk
description	Full Sentry SDK setup for .NET. Use when asked to "add Sentry to .NET", "install Sentry for C#", or configure error monitoring, tracing, profiling, logging, or crons for ASP.NET Core, MAUI, WPF, WinForms, Blazor, Azure Functions, or any other .NET application.
license	Apache-2.0

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)

npx @sentry/wizard@latest -i dotnet

The wizard logs you into Sentry, selects your org and project, configures your DSN, and sets up MSBuild symbol upload for readable stack traces in production.

Skip to Verification after running the wizard.

---

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://[e-mail]/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.

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)