Nuget restore version conflict build error on VSTS

Question

Builds fine locally but getting following error on VSTS build server. Issue is clear but not able to resolve it.

018-07-18T19:41:24.6993903Z ##[error]The nuget command failed with exit code(1) and error(NU1107: Version conflict detected for Microsoft.AspNetCore.Http.Abstractions. Reference the package directly from the project to resolve this issue. 
 webapi.admin -> Microsoft.AspNetCore.Cors 2.1.1 -> Microsoft.AspNetCore.Http.Extensions 2.1.1 -> Microsoft.AspNetCore.Http.Abstractions (>= 2.1.1) 
 webapi.admin -> Microsoft.AspNetCore.App 2.1.0 -> Microsoft.AspNetCore.Http.Abstractions (= 2.1.0).

Answer 1

Can you upgrade Microsoft.AspNetCore.App to version 2.1.1?

Or just upgrade all your nuget references to the latest version? (2.1.2 for these)

As for building locally working, try cleaning, or create a fresh clone of the source control repo and see if that works.

Answer 2

Explicitly setting the version attribute resolved it, changed:

<PackageReference Include="Microsoft.AspNetCore.App" /> to

<PackageReference Include="Microsoft.AspNetCore.App" Version="2.1.1" />

More details here: https://github.com/aspnet/Universe/issues/1180#issuecomment-392180608

Answer 3

I was dealing with these issues too but it was because I simply copied a deployment YAML file from somewhere else and did not use the proper tooling. After following this tutorial, it worked like a charm:

https://docs.microsoft.com/en-us/azure/devops/pipelines/languages/dotnet-core?view=azure-devops

More specifically, I think using the dotnet restore to restore your packages might fix it:

steps:
- script: dotnet restore

Make sure to install the correct .NET Core SDK, too.

steps:
- task: DotNetCoreInstaller@0
  inputs:
    version: '2.1.300' # replace this value with the version that you need for your project