Cannot pass empty string as Dsn from appsettings.json when using generic host builder

Package

Sentry

.NET Flavor

.NET

.NET Version

9.0.0

OS

Android

SDK Version

9.0.101

Self-Hosted Sentry Version

No response

Steps to Reproduce

Run the Sentry.Samples.GenericHost project with "Dsn": "" set in appsettings.json

Expected Result

The application to run with Sentry SDK disabled

Actual Result

System.ArgumentNullException: 'Value cannot be null. (Parameter 'You must supply a DSN to use Sentry.To disable Sentry, pass an empty string: "".See https://docs.sentry.io/platforms/dotnet/configuration/options/#dsn')'

Further details

This seems to affect only setups with generic host builder; with web host setting an empty string in appsettings.json works just fine.

In my setup the call is located within a IHostBuilder.ConfigureLogging, which suffers from this issue as it is similar to the sample above and thus most likely caused by same underlying reason.

My own research showed that dotnet/runtime#62532 and/or dotnet/runtime#65594 might be the root cause of this issue, as the .NET runtime seems to cast empty strings to null in some particular situations. If possible, it would be nice to have a way to prevent this from happening within the scope of the Sentry SDK.

Workaround

When manually setting the DSN with e.g.

builder.Logging.AddSentry((sentryOptions) =>
{
    sentryOptions.Dsn = builder.Configuration["Sentry:Dsn"];
});

the problem does not occur.

@jnoordsij

Thanks for the sleuthing @jnoordsij. 🙏🏻

I added my 2c to the issue in the dotnet/runtime repo.

As a workaround, you could do something like this when initialising Sentry in your generic host:

var builder = Host.CreateApplicationBuilder();

builder.Logging.AddConfiguration(builder.Configuration);
builder.Logging.AddSentry(options =>
{
    options.Dsn = builder.Configuration["Sentry:Dsn"];
});

Here my workaround:

webBuilder.UseSentry(options =>
{
    options.Dsn = options.Dsn ?? string.Empty;
});

From my initial tests on .NET v11.0.0-rc.1.26425.128, which includes dotnet/runtime@d6089ff, this indeed seems fixed.

test(hosting): cover UseSentry and the hosted service on both builders

test(hosting): cover a disabled SDK and starting hosted services in MAUI

feat: add Sentry.Extensions.Hosting with UseSentry for generic host a…

@jnoordsij

Thank you for your report (and support) here, @jnoordsij and @meriturva !

In the .NET SDK version 7.0 (with #5739) we're introducing a new Sentry.Extensions.Hosting package with UseSentry specific for generic host apps. It reads the Sentry section of appsettings.json the same way Sentry.AspNetCore currently does, so "Dsn": "" disables the SDK.

var builder = Host.CreateApplicationBuilder(args);
builder.UseSentry();

{
  "Sentry": {
    "Dsn": ""
  }
}

Host.CreateDefaultBuilder(args).UseSentry() works the same way. The Sentry.Samples.GenericHost sample will now also use UseSentry.

One thing for the upgrade: in 7.0, Logging.AddSentry() no longer initializes the SDK (#5595), so the setup in your ConfigureLogging moves to UseSentry.

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Cannot pass empty string as Dsn from appsettings.json when using generic host builder #3875

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Expected Result

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Further details

Workaround

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Cannot pass empty string as Dsn from appsettings.json when using generic host builder #3875

Description

Package

.NET Flavor

.NET Version

OS

SDK Version

Self-Hosted Sentry Version

Steps to Reproduce

Expected Result

Actual Result

Further details

Workaround

Activity

jamescrosswell commented on Jan 9, 2025

meriturva commented on Sep 23, 2025

14 remaining items

jnoordsij commented on Sep 10, 2026

ric-oliv commented on Oct 19, 2026

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