Umbraco-CMS/src/Umbraco.Web.Common/Security/ConfigureIISServerOptions.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.Options;
using Umbraco.Cms.Core.Configuration.Models;

namespace Umbraco.Cms.Web.Common.Security;

[Obsolete(
    "This class is obsolete, as this does not configure your Maximum request length, see https://our.umbraco.com/documentation/Reference/V9-Config/MaximumUploadSizeSettings/ for information about configuring maximum request length")]
public class ConfigureIISServerOptions : IConfigureOptions<IISServerOptions>
{
    private readonly IOptions<RuntimeSettings> _runtimeSettings;

    public ConfigureIISServerOptions(IOptions<RuntimeSettings> runtimeSettings) =>
        _runtimeSettings = runtimeSettings;

    public void Configure(IISServerOptions options) =>

        // convert from KB to bytes
        options.MaxRequestBodySize = _runtimeSettings.Value.MaxRequestLength.HasValue
            ? _runtimeSettings.Value.MaxRequestLength.Value * 1024
            : uint.MaxValue; // ~4GB is the max supported value for IIS and IIS express.
}