Async lambda (ARCH107)

Key dotnet.async.async-lambda · Severity warning · Category async

Async lambdas that bind to an async void signature are dangerous; exceptions inside them cannot be caught. Add proper error handling, or prefer Task-returning delegates.

Incorrect

timer.Elapsed += async (s, e) =>
{
    await _repository.SaveAsync();
};

Correct

timer.Elapsed += async (s, e) =>
{
    try
    {
        await _repository.SaveAsync();
    }
    catch (Exception ex)
    {
        _logger.LogError(ex, "Save failed");
    }
};

Fix

Wrap the async lambda body in try/catch, or switch to a Func<Task> delegate. If needed, suppress the rule per project/workspace via except/ignore.