NameError: uninitialized constant (rails)

Some things to try:

1. Restart the rails console; changes to your models will only get picked up by a rails console that is already open if you do > reload! (although I have found this to be unpredictable), or by restarting the console.

2. Is your model file called "phone_number.rb" and is it in "/app/models"?

3. You should double-check the "--sandbox" option on your rails console command. AFAIK, this prevents changes. Try it without the switch.

I was getting the error:

NameError: uninitialized constant

Then I noticed that I had accidentally created a plural model so I went back and renamed the model file to singular and also changed the class name in the model file to singular and that solved it.

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