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.net.net-coredotnet-cli

dotnet build produces NullReferenceException

I made a change to a known working project and now I get the following when building with dotnet build:

λ dotnet build
Object reference not set to an instance of an object.

The change was adding a new framework to the frameworks section, which has worked in the past. I'm not sure why it suddenly stopped working.

Solution

  • This is a known bug in the dotnet CLI. It happens if you add a new framework to project.json but don't run dotnet restore.

    Restoring first fixes the issue:

    λ dotnet restore

log  : Restore completed in 2138ms.

λ dotnet build

Compilation succeeded.
    0 Warning(s)
    0 Error(s)