diff --git a/activerecord/lib/active_record/connection_adapters/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/connection_specification.rb
index 09ef0f389ad0721142e3ae69526375153d39563a..d60d31eda4ccdf27ba5df7ea1f6c6fa016d75573 100644
--- a/activerecord/lib/active_record/connection_adapters/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/connection_specification.rb
@@ -227,7 +227,7 @@ def resolve_symbol_connection(spec)
           if config = configurations[spec.to_s]
             resolve_connection(config)
           else
-            raise(AdapterNotSpecified, "'#{spec}' database is not configured. Available configuration: #{configurations.inspect}")
+            raise(AdapterNotSpecified, "'#{spec}' database is not configured. Available: #{configurations.keys.inspect}")
           end
         end