Old Rails and PostgreSQL 12 Problem

3 min readMay 16, 2021

When your Ruby on Rails is an old version and PostgreSQL is new, you will get the panic error since PostgreSQL 12 doesn’t allow the panic value.

For example, we’re using Rails v4.2.1 and try to rake db:create

PG::InvalidParameterValue: ERROR:  invalid value for parameter "client_min_messages": "panic"
HINT:  Available values: debug5, debug4, debug3, debug2, debug1, log, notice, warning, error.
: SET client_min_messages TO 'panic'

The panic will be at line 313

https://github.com/rails/rails/blob/v4.2.1/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb#L313

It’s fixed from panic to warning since Rails v4.2.5 and above.

https://github.com/rails/rails/blob/v4.2.5/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb#L673

So, our purpose is to fix warning level for client_min_messages avoid error if Rails < 4.2.5 and PostgreSQL >= 12.

And these are the solutions I found.

Solution A

Update Rails gem to 4.2.5, fix Gemfile gem 'rails' with this

gem 'rails', '4.2.5'

However, if we tried to update the Rails gem, we also need to update other dependency gems when installing the gem. 😛

Solution B

Find the location gem and fix it directly

$ locate 'activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb'/Users/pagorn/.rvm/gems/ruby-2.3.1/gems/activerecord-4.2.1/lib/active_record/connection_adapters/postgresql_adapter.rb

Use your text editor to edit it. Go to line 313, you should found this code

def set_standard_conforming_strings
  old, self.client_min_messages = client_min_messages, 'panic'

Change panic to warning It should look like this.

def set_standard_conforming_strings
  old, self.client_min_messages = client_min_messages, 'warning'

save it and try rake db:create

I do not recommend this way because when we deploy/clone our project to the new environment, we need to fix it for the first time. Your colleagues will not happy. 😒

Solution C

Fork Rails repository to your Github
Clone it from your fork with specific tag version such as 4.2.1

git clone -b 'v4.2.1' https://github.com/rails/rails.git
cd rails

Checkout a new branch from tag

git checkout -b fix/panic-error-postgresql-12

Fix the panic to warning

def set_standard_conforming_strings
  old, self.client_min_messages = client_min_messages, 'warning'

commit code and push the new change to remote

git add activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
git commit -m 'Fix panic to warning for postgresql 12'
git push -u fix/panic-error-postgresql-12

create tag and push a new tag (optional)

git tag 4.2.1.1
git push origin 4.2.1.1

After that, fix Gemfile to point it to branch or tag

point to branch

gem 'rails', git: 'https://github.com/nrogap/rails.git', branch: 'fix/panic-error-postgresql-12'

or point to tag (optional)

gem 'rails', git: 'https://github.com/nrogap/rails.git', tag: 'v4.2.1.1'

I already made tag v4.2.1.1 on Github for myself 😊

Solution D

Clone the whole rails gem

git clone -b 'v4.2.1' https://github.com/rails/rails.git

Paste it in the vendor folder

Fix the panic similar Solution B, then fix Gemfile

gem 'rails', path: 'vendor/gems/rails-4.2.1.1'

The size of your project folder will be increase by ~22.5MB 🙂

Conclusion

In my opinion, I prefer Solution C and D. It better when you set up and run a project without any additional config.

I also tried the monkey patch solution but doesn’t work with the rake command.

That’s it! Enjoys 🎉