.net core build error when building docker image missing Newtonsoft.Json

Question

I'm trying to build my .net core project onto a docker container but it seems like it can't find Newtonsoft.Json which I thought was included in the asp.net core

Here is my docker file:

FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base
WORKDIR /app
EXPOSE 58373
EXPOSE 44370

FROM microsoft/dotnet:2.1-sdk AS build
WORKDIR /src
COPY ["TestCode/TestCode.csproj", "TestCode/"]
RUN dotnet restore "TestCode/TestCode.csproj"
COPY . .
WORKDIR "/src/TestCode"
RUN dotnet build "TestCode.csproj" -c Release -o /app

FROM build AS publish
RUN dotnet publish "TestCode.csproj" -c Release -o /app

FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "TestCode.dll"]

I'm getting the following error when trying to build Error Could not load file or assembly 'Newtonsoft.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The system cannot find the file specified.

Answer 1

In my case, When used JsonProperty in a class,

Visual Studio intellicode auto-filled,

using Newtonsoft.Json;

Then during docker build,

warning MSB3245: Could not resolve this reference. Could not locate the assembly "Newtonsoft.Json". Check to make sure the assembly exists on disk.

When I checked, found out that the Visual Studio added an Assembly Reference to Newtonsoft.Json (you can find this by expanding Dependencies node in the solution explorer in Visual Studio). And I was using Linux images.

So in order to solve this, I removed the Assembly Reference, and added nuget package Newtonsoft.Json, then the docker build was successful.