sentry-dotnet-sdk

All Skills > SDK Setup > .NET SDK

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 (OTLP export requires ≥6.5.0). 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

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`

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+
⚡ Metrics — counters, gauges, distributions linked to traces; recommend for apps that need custom business metrics
⚡ 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+
Metrics	App needs custom business metrics (request counts, queue depths, response times)
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`

Recommended: Install Sentry.OpenTelemetry.Exporter (≥6.5.0) for OTLP export. Alternatively, use Sentry.OpenTelemetry for the bridge pattern.

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using OpenTelemetry.Trace;
 
// Package: Sentry.OpenTelemetry.Exporter
var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults()
    .ConfigureLogging(logging =>
    {
        logging.AddSentry(options =>
        {
            options.Dsn = "___YOUR_DSN___";
            options.Debug = true;
            options.TracesSampleRate = 1.0;
            options.UseOtlp(); // send OTel spans via OTLP (requires 6.5.0+)
        });
    })
    .ConfigureServices(services =>
    {
        services.AddOpenTelemetry().WithTracing(builder =>
        {
            builder
                .AddHttpClientInstrumentation()
                .AddSentryOtlpExporter("___YOUR_DSN___"); // route spans to Sentry OTLP endpoint
        });
    })
    .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. The SDK uploads PDB files (and optionally sources) via MSBuild properties on Release builds:

<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>

Upload needs a SENTRY_AUTH_TOKEN set in CI (a secret). For creating the token and the CI wiring, see sentry-source-maps. The SentryCreateRelease / SentrySetCommits properties also create a release with suspect commits — see sentry-releases.

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
Metrics	`references/metrics.md`	Custom counters, gauges, distributions; `EmitCounter`, `EmitGauge`, `EmitDistribution`
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.

Configuration 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
`TraceIgnoreStatusCodes`	`IList<HttpStatusCodeRange>`	`[]`	—	Drop transactions whose HTTP response status matches any range; e.g., `[404]` or `[(500, 599)]`
`StrictTraceContinuation`	`bool`	`false`	—	When `true`, starts a new trace if exactly one side (SDK or incoming `sentry-org_id` baggage) has an org ID. A full mismatch (both present but different) always starts a new trace regardless of this setting. (requires ≥6.6.0)
`OrgId`	`string`	auto	—	Organization ID for trace validation; auto-parsed from DSN subdomain (e.g., `o123.ingest.sentry.io` → `"123"`). Recommended to set explicitly for self-hosted Sentry, local Relay, or custom domains (requires ≥6.6.0)

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

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>`

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`)

All Skills > SDK Setup > .NET SDK

Sentry .NET SDK

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 (OTLP export requires ≥6.5.0). 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

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`

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+
⚡ Metrics — counters, gauges, distributions linked to traces; recommend for apps that need custom business metrics
⚡ 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+
Metrics	App needs custom business metrics (request counts, queue depths, response times)
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`

Recommended: Install Sentry.OpenTelemetry.Exporter (≥6.5.0) for OTLP export. Alternatively, use Sentry.OpenTelemetry for the bridge pattern.

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using OpenTelemetry.Trace;
 
// Package: Sentry.OpenTelemetry.Exporter
var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults()
    .ConfigureLogging(logging =>
    {
        logging.AddSentry(options =>
        {
            options.Dsn = "___YOUR_DSN___";
            options.Debug = true;
            options.TracesSampleRate = 1.0;
            options.UseOtlp(); // send OTel spans via OTLP (requires 6.5.0+)
        });
    })
    .ConfigureServices(services =>
    {
        services.AddOpenTelemetry().WithTracing(builder =>
        {
            builder
                .AddHttpClientInstrumentation()
                .AddSentryOtlpExporter("___YOUR_DSN___"); // route spans to Sentry OTLP endpoint
        });
    })
    .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. The SDK uploads PDB files (and optionally sources) via MSBuild properties on Release builds:

<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>

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
Metrics	`references/metrics.md`	Custom counters, gauges, distributions; `EmitCounter`, `EmitGauge`, `EmitDistribution`
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.

Configuration 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
`TraceIgnoreStatusCodes`	`IList<HttpStatusCodeRange>`	`[]`	—	Drop transactions whose HTTP response status matches any range; e.g., `[404]` or `[(500, 599)]`
`StrictTraceContinuation`	`bool`	`false`	—	When `true`, starts a new trace if exactly one side (SDK or incoming `sentry-org_id` baggage) has an org ID. A full mismatch (both present but different) always starts a new trace regardless of this setting. (requires ≥6.6.0)
`OrgId`	`string`	auto	—	Organization ID for trace validation; auto-parsed from DSN subdomain (e.g., `o123.ingest.sentry.io` → `"123"`). Recommended to set explicitly for self-hosted Sentry, local Relay, or custom domains (requires ≥6.6.0)

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

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>`

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`)

Documentation

Documentation

Sentry .NET SDK

Invoke This Skill When

Phase 1: Detect

Phase 2: Recommend

Phase 3: Guide

Option 1: Wizard (Recommended)

Option 2: Manual Setup

Install the right package

ASP.NET Core — Program.cs

WPF — App.xaml.cs

WinForms — Program.cs

.NET MAUI — MauiProgram.cs

Blazor WebAssembly — Program.cs

Azure Functions (Isolated Worker) — Program.cs

AWS Lambda — LambdaEntryPoint.cs

Classic ASP.NET — Global.asax.cs

Symbol Upload (Readable Stack Traces)

For Each Agreed Feature

Configuration Reference

Core SentryOptions

ASP.NET Core Extended Options (SentryAspNetCoreOptions)

MAUI Extended Options (SentryMauiOptions)

Environment Variables

MSBuild Symbol Upload Properties

Verification

Phase 4: Cross-Link

Troubleshooting

Documentation

sentry-dotnet-sdk

Documentation

Sentry .NET SDK

Invoke This Skill When

Phase 1: Detect

Phase 2: Recommend

Phase 3: Guide

Option 1: Wizard (Recommended)

Option 2: Manual Setup

Install the right package

ASP.NET Core — Program.cs

WPF — App.xaml.cs

WinForms — Program.cs

.NET MAUI — MauiProgram.cs

Blazor WebAssembly — Program.cs

Azure Functions (Isolated Worker) — Program.cs

AWS Lambda — LambdaEntryPoint.cs

Classic ASP.NET — Global.asax.cs

Symbol Upload (Readable Stack Traces)

For Each Agreed Feature

Configuration Reference

Core SentryOptions

ASP.NET Core Extended Options (SentryAspNetCoreOptions)

MAUI Extended Options (SentryMauiOptions)

Environment Variables

MSBuild Symbol Upload Properties

Verification

Phase 4: Cross-Link

Troubleshooting

ASP.NET Core — `Program.cs`

WPF — `App.xaml.cs`

WinForms — `Program.cs`

.NET MAUI — `MauiProgram.cs`

Blazor WebAssembly — `Program.cs`

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

AWS Lambda — `LambdaEntryPoint.cs`

Classic ASP.NET — `Global.asax.cs`

Core `SentryOptions`

ASP.NET Core Extended Options (`SentryAspNetCoreOptions`)

MAUI Extended Options (`SentryMauiOptions`)

ASP.NET Core — `Program.cs`

WPF — `App.xaml.cs`

WinForms — `Program.cs`

.NET MAUI — `MauiProgram.cs`

Blazor WebAssembly — `Program.cs`

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

AWS Lambda — `LambdaEntryPoint.cs`

Classic ASP.NET — `Global.asax.cs`

Core `SentryOptions`

ASP.NET Core Extended Options (`SentryAspNetCoreOptions`)

MAUI Extended Options (`SentryMauiOptions`)