3.4.0.4 Slim Application Error when 'Record Decision' operate!

Everything is working fine last week ,but today can not do ‘Record Decision’


PHP error below
AH01071: Got error ‘PHP message: Slim Application Error:\nType: Error\nMessage: Class "PKP\security\authorization\internal\SubmissionCompletePolicy" not found\nFile: /var/www/vhosts/elmerjournals.com/jocmr.elmerjournals.com/lib/pkp/api/v1/submissions/PKPSubmissionHandler.php\nLine: 289\nTrace: #0 /var/www/vhosts/elmerjournals.com/jocmr.elmerjournals.com/lib/pkp/classes/security/authorization/internal/ApiAuthorizationMiddleware.php(53): PKP\API\v1\submissions\PKPSubmissionHandler->authorize()\n#1 /var/www/vhosts/elmerjournals.com/jocmr.elmerjournals.com/lib/pkp/classes/security/authorization/internal/ApiAuthorizationMiddleware.php(85): PKP\security\authorization\internal\ApiAuthorizationMiddleware->_authorize()\n#2 [internal function]: PKP\security\authorization\internal\ApiAuthorizationMiddleware->__invoke()\n#3 /var/www/vhosts/elmerjournals.com/jocmr.elmerjournals.com/lib/pkp/lib/vendor/slim/slim/Slim/DeferredCallable.php(57): call_user_func_array()\n#4 [internal function]: Slim\DeferredCallable->__invoke()\n#5 /var/www/vho…’, referer: https://jocmr.elmerjournals.com/jocmr/decision/record/6016?decision=2&reviewRoundId=9

i used the backup webfiles it is go worked now.But still do not know why have get this error