New nullable issue when on .net 9

[FvS-MR]

Hi,
like in issue #594 i ran into a new nullable issue.

In HtmlNode I see a lot of code like this:

#if NET8_0
HtmlNodeCollection?
#else
HtmlNodeCollection
#endif

This gives me false nullable warnings (return value can not be null regarding the interface) in .net 9 projects.
I think all code like this should be changed to

#IF NET8_0_OR_GREATER

[JonathanMagnan]

Hello @FvS-MR,

Could you provide a minimal project that reproduces the warning? I thought compiling HAP with .NET 7 would remove them, as this should start only with projects compiled with .NET 8 or later.

I tried to reproduce it with the latest version but was unsuccessful (it was easy with v1.12.1).

Best Regards,

Jon

[FvS-MR]

Sure. For its really short and I am not allowed to upload a csproj I wil just paste it all as text.

ConsoleApp1.csproj:

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net9.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
    </PropertyGroup>

    <ItemGroup>
      <PackageReference Include="HtmlAgilityPack" Version="1.12.2" />
    </ItemGroup>

</Project>

Program.cs:

using HtmlAgilityPack;

var document = new HtmlDocument();
document.LoadHtml(string.Empty);

//Here my ide shows that the conditional access can be removed
var nodes = document.DocumentNode.SelectNodes("Fake")?.ToArray() ?? [];
Console.WriteLine(nodes.Length);

[JonathanMagnan]

That’s weird — I still don’t get the warning on my brand-new laptop, nor on any of my older PCs.

[FvS-MR]

I am using Rider 2025.2.0.1

[trejjam]

I described the issue in the #597. One of the issues is that the conditional directives use #if NET8_0, but the library is published under net7. So the minimal fix is to replace #if NET8_0 with #if NET7_0.

To prevent the issue from recurring, it's a good idea to use the *_OR_GREATER directive.

The error is not present when your solution is not using nullable annotations, which might be why there is a difference between @JonathanMagnan and @FvS-MR .

As stated in the #597, I am happy to create a PR for this if there is a desire.

[wjrogers]

@JonathanMagnan You can target .NET 8.0 (and later) without nullable analysis. If you don't want to support nullable analysis, you should remove this line:

html-agility-pack/src/HtmlAgilityPack.Net7/HtmlAgilityPack.Net7.csproj

Line 8 in 64a718a

<Nullable>enable</Nullable>

(and then remove any existing nullable annotations from your source files)

[JonathanMagnan]

Hello @wjrogers ,

Thank you, that will be part for the next time we release this library.

@trejjam , there is already several pull request about this. I will try to make it happens in very early 2026 as so many people ask for it but at this moment, it's just impossible to fully support it.

Best Regards,

Jon