NU1101Unable to find package DevExpress.ExpressApp.Persistent.Base. No packages exist with this id in source(s):

I am trying to set up packages for a WinForms XAF XPO Standard Security Application.I used the wizard to create the solution.Then the project updaterThen I edited the project file package references.However when I try to build the .exe project I get

NU1101  Unable to find package DevExpress.ExpressApp.Persistent.Base. No packages exist with this id in source(s):

Even though the package shows in the references.

I tried checking the installed packages