Please help us help you and fill where relevant:
Your LimeSurvey version: Version 5.6.11+230320
Own server or LimeSurvey hosting:Own Server
Survey theme/template:
==================
After moving from version 3 to 5 I receive the below error when activating a survey. AWS EC2 for frontend, AWS Aurora serverless database - MySQL (Engine 5.7.x). 500: Internal Server ErrorCDbCommand failed to execute the SQL statement: SQLSTATE[HY000]: General error: 1238 Variable 'default_storage_engine' is a read only variable
Thanks
 

It appears to be something in this file. I have also confirmed all of my tables are InnoDB.

github.com/LimeSurvey/LimeSurvey/blob/fe.../SurveyActivator.php

SQL Debug show this which seems odd -
system.db.CDbCommand.execute(SET default_storage_engine=MyISAM;) 1 0.00212 0.00212 0.00212 0.00212

I'm guessing there is a better fix but this works for me. Output of debug. - system.db.CDbCommand.execute(SET default_storage_engine=innoDB) which is a change from the above post and what appears to have fixed it. 

Change in SurveyActivator.php -
$db->createCommand(new CDbExpression(sprintf('SET default_storage_engine=innoDB')))

When you update : you set InnoDB for MySQL ?

I think the issue is here : when updating for 3.X : it can be only MyISAM.

The system must not check the settings you choose, but only the current settings.

I think we have same issue if we remove a config.php file from a MyISAM setup (or InnoçDB and chose MyIsam).