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.NET runtime no longer provides default SIGTERM signal handler

On Unix systems, the .NET runtime no longer provides a default SIGTERM signal handler. On Windows, the .NET runtime no longer provides default handlers for the CTRL_CLOSE_EVENT and CTRL_SHUTDOWN_EVENT signals, which are equivalents of Unix SIGTERM signal.

This change reverts the SIGTERM signal handling behavior to what it used to be in .NET Framework and classic Mono runtime.

Version introduced

.NET 10 Preview 5

Previous behavior

Previously, a SIGTERM signal handler registered by the .NET runtime by default triggered graceful application exit. AppDomain.ProcessExit and AssemblyLoadContext.Unloading events were raised before the application exited.

New behavior

Starting in .NET 10, the .NET runtime does not override SIGTERM signal handling provided by the operating system. The typical default SIGTERM signal handler provided by the operating system terminates the application immediately. AppDomain.ProcessExit and AssemblyLoadContext.Unloading events aren't raised.

Type of breaking change

This is a behavioral change.

Reason for change

The SIGTERM signal handler registered by the .NET runtime by default was both insufficient for some app models (for example, console and containerized applications) and incompatible with other app models (for example, Windows services). It's better to leave it to higher-level libraries or application code to register signal handlers appropriate for the given app model.

  • No action is necessary for typical ASP.NET applications or applications that use higher-level APIs such as HostingHostBuilderExtensions.UseConsoleLifetime to handle app-model specific concerns. These higher-level APIs register handlers for SIGTERM and other signals as appropriate.

  • If you want to handle SIGTERM signal without taking a dependency on higher-level libraries, you can replicate the previous behavior by creating a SIGTERM signal handler in your Main method using the PosixSignalRegistration.Create API:

static void Main()
{
    using var termSignalRegistration =
        PosixSignalRegistration.Create(
            PosixSignal.SIGTERM,
            (_) => Environment.Exit(0));

    // Your application code here
}

Affected APIs