warning : All projects referencing MyProject.csproj must install nuget package Microsoft.Bcl.Build

The answer provided by TheESJ is correct, however the wording wasn't clear to me. Since I cannot comment on the answer, I will provide more details here. Specifically, I was having this problem with an Azure project and the following workaround was required to make the warning go away:

When you double-click the warning in VisualStudio, you will be taken to the BclBuildValidateNugetPackageReferences target in the Microsoft.BclBuild.targets file. Above the actual target element, you should find a large comment block that talks about disabling the project reference checks. Since Azure projects cannot have any library references, it is impossible for those Azure projects to fulfill the requirements of this particular build target.

The solution? Disable reference checking from the Azure project since it is impossible to actually add a nuget package reference.

EXAMPLE

So, assume we have two projects: MyAzureProject.ccproj which references MyProject.csproj. Follow these steps:

Right-click on "MyAzureProject" in the Solution Explorer and select "Edit Project File." Find the project reference to "MyProject." It should look something like: MyProject {1d99490e-d140-4897-9890-238e673a5864} ... Add the following element inside of the ProjectReference element: SkipValidatePackageReferences=true Your project reference should now look like this: MyProject {1d99490e-d140-4897-9890-238e673a5864} ... SkipValidatePackageReferences=true Right-click on "MyAzureProject" in Solution Explorer and choose "Reload Project."

You should now be able to rebuild and the error should be gone.

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If you double click the warning it gives you instructions for disabling the warning.

It is safe to disable for projectreferences from projects that don't yet support Nuget.

See below portion in bold copied from Microsoft.Bcl.Build.targets.

BclBuildValidateNugetPackageReferences

This target can be disabled for a project reference by setting SkipValidatePackageReferences=true for the reference:

<ProjectReference Include="..\pcl\pcl.csproj">
  <Project>{664a9e98-fac7-4567-a046-0dde95fddb48}</Project>
  <Name>pcl</Name>
  <Properties>SkipValidatePackageReferences=true</Properties>
</ProjectReference>

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I faced the same issue and was trying to update Microsoft.Bcl.Build.targets; which did not help.

After some investigation found that .csproj file of the Azure Service project must be modified to include <Properties>SkipValidatePackageReferences=true</Properties>.

This was not apparent from the answer of @TheESJ and so decided to post separate answer. Thanks to @TheESJ.

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I encountered this issue a number of times, and the Properties method does indeed work, but when dealing with a Wix project, I had to do the following instead:

<AdditionalProperties>SkipValidatePackageReferences=true</AdditionalProperties>

When I used the Properties Xml node, I got a new error:

The OutputPath property is not set for project 'MyInstallerProject.csproj'. Please check to make sure that you have specified a valid combination of Configuration and Platform for this project. Configuration='Debug' Platform='x86'. This error may also appear if some other project is trying to follow a project-to-project reference to this project, this project has been unloaded or is not included in the solution, and the referencing project does not build using the same or an equivalent Configuration or Platform.

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After failing to resolve the issues with any of the above answers, I simply followed the instructions contained within the Microsoft.Bcl.Build.targets file (displayed after double clicking on the error in the build output window). I unloaded my project (referencing Azure packages), encountering the error. Edited the project file and inserted the following...

<PropertyGroup>
      <SkipValidatePackageReferences>true</SkipValidatePackageReferences>
</PropertyGroup>

...at the top of the project file before the first PropertyGroup.

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