以下のエラーが出た場合

DEPRECATION WARNING: Leaving `ActiveRecord::ConnectionAdapters::SQLite3Adapter.represent_boolean_as_integer`
set to false is deprecated. SQLite databases have used 't' and 'f' to serialize
boolean values and must have old data converted to 1 and 0 (its native boolean
serialization) before setting this flag to true. Conversion can be accomplished
by setting up a rake task which runs

  ExampleModel.where("boolean_column = 't'").update_all(boolean_column: 1)
  ExampleModel.where("boolean_column = 'f'").update_all(boolean_column: 0)

for all models and all boolean columns, after which the flag must be set to
true by adding the following to your application.rb file:

  Rails.application.config.active_record.sqlite3.represent_boolean_as_integer = true
 (called from instance_eval at /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.2.4.3/lib/active_support/lazy_load_hooks.rb:71)
Started GET "/" for 122.26.15.2 at 2020-08-09 10:47:48 +0000
Cannot render console from 122.26.15.2! Allowed networks: 127.0.0.1,

以下を追加

application.rb

(省略)

Rails.application.config.active_record.sqlite3.represent_boolean_as_integer = true

以上。