No longer able to update IdentityServer/IdentityModel on .NET 9?

[promim]

After updating Duende.IdentityModel in my .NET 9 project (7.1.0 -> 8.0.0), I started getting the following warning:

Found conflicts between different versions of "System.Text.Json" that could not be resolved. 3>...\Microsoft.Common.CurrentVersion.targets(2433,5): warning MSB3277: There was a conflict between "System.Text.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" and "System.Text.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51". 3>...\Microsoft.Common.CurrentVersion.targets(2433,5): warning MSB3277: "System.Text.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" was chosen because it was primary and "System.Text.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" was not. 3>...\Microsoft.Common.CurrentVersion.targets(2433,5): warning MSB3277: References which depend on "System.Text.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" [...\dotnet\packs\Microsoft.NETCore.App.Ref\9.0.11\ref\net9.0\System.Text.Json.dll].

That's because the Duende.IdentityModel dependency that I updated has a dependency of System.Text.Json from .NET 10, which I guess should still be backwards compatible with .NET 9. Downgrading the transitive System.Text.Json to 9.* ends up in a version conflict error.

Updating Duende.IdentityServer from 7.3.2 to anything higher results in a similar problem.
Duende.IdentityServer references Duende.IdentityServer.Storage, which references Duende.IdentityModel 8.0.0 and so on.

Does that mean that .NET 9 support has already been cut and my only option is to upgrade to .NET 10?

[wcabus]

Duende IdentityServer 7.1 and higher still supports .NET 9 until the end-of-life date of November 10, 2026. And while Duende.IdentityModel 8.0.0 doesn't explicitly target .NET 9, it is compatible with this version of .NET.

System.Text.Json 10.x is also indeed still backwards compatible, so if you haven't done so already, try adding an explicit reference to the NuGet package in your project, targeting at least version 10.0.0 of the System.Text.Json NuGet package.

[promim]

Duende IdentityServer 7.1 and higher still supports .NET 9 until the end-of-life date of November 10, 2026. And while Duende.IdentityModel 8.0.0 doesn't explicitly target .NET 9, it is compatible with this version of .NET.

System.Text.Json 10.x is also indeed still backwards compatible, so if you haven't done so already, try adding an explicit reference to the NuGet package in your project, targeting at least version 10.0.0 of the System.Text.Json NuGet package.

Yes, adding the explicit reference certainly works, I was just a bit worried as I've seen backwards compatibility issues with Microsoft packages in older .NET versions. I guess things are better these days. :)