NoMethodError: undefined method `setup'for Devise: Module

Prerequisites

--PaaS related settings such as AWS have been completed --SQL is already implemented --Deploy to Heroku

Error statement

rake aborted!
       NoMethodError: undefined method `setup' for Devise:Module

Conclusion

Write gem'devise' in the production environment, not in the group develop test

Cause

In the repository config/environment, there are rb files for production, deveropment, and test, and if you enclose the gem in a group, the gem cannot be used in production.rb.