Question: `models/foo_abc.rb`

```
class FooABC
  ...

```

Raises

```
NameError:
       uninitialized constant FooABC

```

How to get it to work in Rails 6?

Answer: 
I'm gonna answer this because it's look like a bug (?). If it's documented elsewhere we can delete this:

```sh
$ bundle exec rails c

irb(main):001:0> FooABC
Traceback (most recent call last):
        1: from (irb):1
NameError (uninitialized constant FooABC)
Did you mean?  FooAbc

irb(main):002:0> FooAbc
Traceback (most recent call last):
        2: from (irb):2
        1: from (irb):2:in `rescue in irb_binding'
NameError (expected file /Users/user/app/models/foo_abc.rb to define constant FooAbc, but didn't)

irb(main):003:0> FooABC
=> FooABC

```

So in this case is better you rename your class.
Where did you run this? On the production?
If run this on the production, try following like this :

```
 spring stop

```

Then run `rails console`.

Also, check your model name.