Undefined method raise_in_transactional_callbacks=' for ActiveRecord::Base:Class (NoMethodError)

Question

Before writing this question I looked at these answers, but was unable to find a solution.:

Error when execute rails generate scaffold User name:string email:string

Answer 1

I had the same issue when upgrading an app from Rails 5.0.1 to Rails 5.1.0.beta1.

When starting the server (rails s), I got the following error message:

/home/user01/.rvm/gems/ruby-2.4.0@global/gems/activerecord-5.1.0.beta1/lib/active_record/dynamic_matchers.rb:22:in `method_missing': undefined method `raise_in_transactional_callbacks=' for ActiveRecord::Base:Class (NoMethodError)

Same ills, same cures.

Commenting out the following line, in config/application.rb, solved the issue...

config.active_record.raise_in_transactional_callbacks = true

After some investigation, I found that this line was default in Rails 4.2.1, vanished in Rails 5.0.0, and now raises an error in Rails 5.1.0.beta1...