When I create a migration bundle and do not specify a runtime, it looks like the subsequent build step does not specify a runtime. The creation of the bundle (from the verbose logging: dotnet publish --runtime win-x64) however does specify a runtime. This part then fails with 'error NETSDK1112: The runtime pack for Microsoft.NETCore.App.Runtime.win-x64 was not downloaded.'.

I can work around this by running a build specifying the runtime, and then a 'dotnet ef migrations bundle --no-build' succeeds.

So for example on my windows dev machine this fails:

dotnet ef migrations bundle -r linux-x64 -v

error: 'error NETSDK1112: The runtime pack for Microsoft.NETCore.App.Runtime.linux-x64 was not downloaded. Try running a NuGet restore with the RuntimeIdentifier 'linux-x64''

and this succeeds:

dotnet build -r linux-x64
dotnet ef migrations bundle -r linux-x64 --no-build

I think that when creating a bundle, the build and publishing of the bundle should specify the same runtime.