(OJS 3.3.0.10) PHP Fatal error: Uncaught PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry

We have upgraded OJS 2.4 to OJS 3.3.0.10. everything is normal but some time following error occurred.

PHP Fatal error: Uncaught PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry ‘vbfflaje1bgqnrsrp22lo8vrfd’ for key ‘sessions.sessions_pkey’ in /EPUB/ojs/lib/pkp/lib/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:115
Stack trace:
#0 /EPUB/ojs/lib/pkp/lib/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php(115): PDOStatement->execute()
#1 /EPUB/ojs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(489): Doctrine\DBAL\Driver\PDOStatement->execute()
#2 /EPUB/ojs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(664): Illuminate\Database\Connection->Illuminate\Database{closure}()
#3 /EPUB/ojs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(631): Illuminate\Database\Connection->runQueryCallback()
#4 /EPUB/ojs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php(496): Illuminate\Database\Connection->run()
#5 /EPUB/ojs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Dat in /EPUB/ojs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Connection.php on line 671

You can just manually delete all rows in sessions table, and the duplicate keys will be solved.