error APPX1685: Default language 'en-150' is not valid

If Visual Studio gives you the following warning and error…

1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(4401,5): warning APPX1901: The DefaultLanguage property is either missing from the project file or does not have a value. The fallback language is set to the Visual Studio language: en-150.
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(4401,5): error APPX1685: Default language 'en-150' is not valid. For a list of supported values, see

…no default language has been set. In my team, my machine (with a mixture of german, dutch and english settings) was the only one producing this error. I tried changing my all language/region settings to US english but it didn’t solve the problem. The only way I could solve the problem was setting the language directly in the project file (.csproj). The element you need to add is DefaultLanguage:

<?xml version="1.0" encoding="utf-8"?>