Rails: No connection pool for ActiveRecord::Base

Question

I\'m trying to use rails 4.2.6 to develop an app. I\'m trying to use postgres for database. Server starts fine but when I try loading a page it throws this \"No connection p

Answer 1

This issue arises when the server cannot find the corresponding database it depends on to pull data from.

I had same issue from my end, I updated my version of Sqlite3, and it was higher than the version that the current Puma Server version supports.

I simply had to uninstall the Sqlite3 version, and then install the version supported by the current version of Puma Server.

gem uninstall sqlite3

This will uninstall the updated version of Sqlite3, and then you run the code below stating the version supported by your current server.

gem install sqlite3

Or you can as well open your Gemfile, and then include the version for the database that you are using

gem 'sqlite3', '~> 1.3.6' 

N/B: The sqlite3 version is the most current version as at the time of writing this answer

And then run

bundle update

to install the version of the database that you specified.

That's all.

I hope this helps.