Fatal error: require_once(): Failed opening required 'CRM/Core/Payment/SDD.php'
If you have performed path reset than path of extension must have been updated and the system already have SDD payment processor created therefore it is throwing file not found error.

You can fix this in either of 3 ways:


If you have db access then update civicrm_payment_processor.is_active = 0 for SDD payment processor type and then update the extension directory path by navigating to Administer >> System Settings >> Directories
Update the extension directory path in civicrm_setting table where name = extensionsDir (make sure you serialize the data correctly)
Over-ride the extension directory path in civicrm.settings.php

$civicrm_setting['Directory Preferences']['extensionsDir'] = 'xxx/sites/default/files/civicrm/persist/contribute/';


and then update the directory path by navigating to Administer >> System Settings >> Directories

HTH

Pradeep