I have been working on a site which was recently upgraded from 3.4.8 to 4.6.0 I am getting an error in error log which states that
Warning: require_once(CRM/Core/Payment/SecurePay.php): failed to open stream: No such file or directory in Civi\Payment\System::getByProcessor() (line 52 of /sites/all/modules/civicrm/Civi/Payment/System.php)
I did not find any civicrm extension with respect to SecurePay. I found securepay file here which i placed at CRM/Core/Payment/SecurePay.php :https://github.com/hash-bang/PHP-SecurePay
Only if go to database and disable securepay payment processor it fixes the error
UPDATE `pysecure_civi3`.`civicrm_payment_processor` SET `is_active` = '0' WHERE `civicrm_payment_processor`.`id` = 4;
where id= 4 is securepay payment processor.