NameError: uninitialized constant (rails)

Question

I have a simple model called PhoneNumber:

class PhoneNumber < ActiveRecord::Base
  validates :pnumber, presence: true, on: :create #=> { :message =>         


        

Answer 1

I started having this issue after upgrading from Rails 5.1 to 5.2
It got solved with:

spring stop
spring binstub --all
spring start
rails s