1 files changed, 6 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb
index 3ab0f28c9b..4c4afb4dbd 100644
--- a/activerecord/lib/active_record/migration/command_recorder.rb
+++ b/activerecord/lib/active_record/migration/command_recorder.rb
@@ -81,7 +81,12 @@ module ActiveRecord
       # invert the +command+.
       def inverse_of(command, args, &block)
         method = :"invert_#{command}"
-        raise IrreversibleMigration unless respond_to?(method, true)
+        raise IrreversibleMigration, <<-MSG.strip_heredoc unless respond_to?(method, true)
+          This migration uses #{command}, which is not automatically reversible.
+          To make the migration reversible you can either:
+          1. Define #up and #down methods in place of the #change method.
+          2. Use the #reversible method to define reversible behavior.
+        MSG
         send(method, args, &block)
       end