Error on POS load - ImportError: No module named past.builtins

Maybe try this - I have never tried it myself!
"
go to DOCTYPEs, enter to the doctype with issues and click on save. Reload and it will work:)
"

@Florea_Andrei kindly suggests that one here ERPNext version 10 frappe install error : ImportError: No module named chat - #5 by ashish-greycube