Add detailed error message to `IrreversibleMigration`

1 files changed, 1 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb
index b52e89d792..ab5a4cad89 100644
--- a/activerecord/lib/active_record/migration/command_recorder.rb
+++ b/activerecord/lib/active_record/migration/command_recorder.rb
@@ -69,7 +69,7 @@ module ActiveRecord
       # invert the +command+.
       def inverse_of(command, args, &block)
         method = :"invert_#{command}"
-        raise IrreversibleMigration unless respond_to?(method, true)
+        raise IrreversibleMigration, "#{method} is not defined, so #{command} is not reversible" unless respond_to?(method, true)
         send(method, args, &block)
       end