Could not find order in db

Hi there after installing this addon getting error on payment page 

Error log 

[27-Aug-2019 22:07:01 Europe/London] Fatal error: Could not find order in database (ID: 25) in ~/includes/controllers/ctrl_order.inc.php on line 97
← ~/includes/controllers/ctrl_order.inc.php on line 9 in load()
← ~/pages/ajax/checkout_summary.html.inc.php on line 16 in __construct()
← ~/index.php on line 35 in include()
Request: POST /shop/ajax/checkout_summary.html HTTP/1.1
Client: 2.25.224.151 (2.25.224.151)
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36

Thanks
Working again
You probably had an incomplete order in session that was removed meantime in the backend.
Now I'm getting that error.

[13-Sep-2019 10:45:10 America/New_York] Fatal error: Could not find order in database (ID: 18) in ~/includes/controllers/ctrl_order.inc.php on line 97
← ~/includes/controllers/ctrl_order.inc.php on line 9 in load()
← ~/pages/ajax/checkout_summary.html.inc.php on line 16 in __construct()
← ~/index.php on line 35 in include()
Request: POST /ajax/checkout_summary.html HTTP/1.0
Client: 66.86.9.52 (66.86.9.52)
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36

What do I need to do?
OK it's working again. So this is a issue with the browser, not the website, correct?
Correct. If you tamper with the database while the order is in your browser session there can be trouble. The lines to fiddle with are pages/ajax/checkout_summary.inc.php line 16-21:

// Resume incomplete order in session
  if (!empty(session::$data['order']->data['id'])) {
    session::$data['order'] = new ent_order(session::$data['order']->data['id']);
  } else {
    session::$data['order'] = new ent_order();
  }
Note this code is from 2.2 but is very similar in earlier versions.