MonoGame.Content.Builder exited with code 9009

When I try to build my game I get this error:
Error The command “…\packages\MonoGame.Content.Builder.\tasks\net46…/…/build\MGCB\build/MGCB.exe /@:“C:…\Content\Content.mgcb” /platform:MacOSX /quiet /outputDir:“bin\MacOSX\Content” /intermediateDir:“obj\MacOSX\Content”” exited with code 9009.

I am trying to update to the new versions of Monogame and Monogame.Extended. Do no understand where this command comes from. Am not doing anything with MacOSX. My platform is Windows.

Hopefully someone can help. Thanks in advance.

Try opening your Content.mgcb file in a text editor.
You might’ve accidentally set some content to build for Mac.

If I recall correctly, I believe this command comes from the .targets file reference in your .csproj file. This is how MonoGame tells the Content Pipeline to build your content when you compile your code.

Thanks for the reply.
I opened my content.mgcb file in Notepad and found no reference to anything other than windows.
However in my project file there are .targets to several platforms including ios andMacOsX. Is it possible that I am missing a NuGet package for MacOSX?