• Newtonsoft.Json has a bug - yes! this actually happens on one of the most popular/used nuget packages
• We want to patch the bug and make sure all our projects and their transitive packages use this version, instead

These answers were provided with the help of

• Martin Ullrich aka @dasmulli.
• Patrick Westerhoff aka @poke
• Alexandre Hertogs aka @TeBeCo

Also refer to this StackOverflow question I asked and they answered.

git clone ... etc

This is your custom code

This is a bit tricky. We need to export something called a "public key" to a file. We then will use this file, later on.

Easiest way to do this is to find an existing copy of the newtonsoft.json.nupkg file. For windows, this is:

C:\Users\<username>\.nuget\packages\newtonsoft.json\12.0.3\lib\netstandard2.0>sn -e Newtonsoft.Json.dll backup-newtonsoft.json-public-key.snk

Notice the:

• username in the path. Change to whatever yours is
• the version in the path. I'm doing this against v 12.0.3.

Then copy the backup-newtonsoft.json-public-key.snk to your fork + cloned repo and copy it to the <repo root>\src\Newtonsoft.Json\ folder.

First change the version in these places (using SEMVER):

    <AssemblyVersion>12.1.0.0</AssemblyVersion>
    <FileVersion>12.1.0</FileVersion>
    <VersionPrefix>12.1.0</VersionPrefix>
    <VersionSuffix>beta1</VersionSuffix>

Next add the delay signing stuff. This uses that file you exported in step #3, above:

    <SignAssembly>true</SignAssembly>
    <AssemblyOriginatorKeyFile>backup-newtonsoft.json-public-key.snk</AssemblyOriginatorKeyFile>
    <DelaySign>true</DelaySign>

I added this _right underneath the last item in this <PropertyGroup>:

    <EmbedUntrackedSources>true</EmbedUntrackedSources>  <-- last line
    <SignAssembly>true</SignAssembly>                    <-- start of new lines I've added
    ..... etc .....

From the repo root:

dotnet pack -c RELEASE -o .\custom-nuget-packages\ .\Newtonsoft.Json\Newtonsoft.Json.csproj

This will now create the NuGet packages in a new custom-nuget-packages folder.

Now copy these newly generated nuget packages (.nupkg and .snupkg) from this repo to your own other/custom repo.

e.g.

<other-repo-root>/custom-nuget-packages/Newtonsoft.Json.12.1.0-beta1.nupkg

To use this nuget package, we need to be able to 'find' them. The easiest way to is to add (or update if it already exists) a nuget.config file:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageSources>
    <add key="localhost-custom-nugets" value="custom-nugets/" />
  </packageSources>
</configuration>

This adds a new nuget location to any existing configuration settings.

And we're done. Add this to your .csproj

<PackageReference Include="Newtonsoft.Json" Version="12.1.0-beta1" />

I've included 2x sample demo's to demonstrate

• ❌ not working (the dll was not delayed signed)
• ✅ working

With the not working, you will notice that it doesn't compile because it's still after a specific version of Newtonsoft.Json

With the working one, it compiles.

Finally, I added a NEW method to my custom Newtonsoft.Json library to proove that my code is using my custom version:

// Proof -> my custom Newtonsoft.Json dll is being used.
Console.WriteLine(JsonConvert.HelloWorldTest());