Upgrade to 3.1 problem

During an upgrade a series of errors reported which preventing projectorria to start :
2013-01-15 09:59:22 ***** ERROR ***** ERROR *****
2013-01-15 09:59:22 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 09:59:22 ***** ERROR ***** cause = Array to string conversion
2013-01-15 09:59:24 ***** ERROR ***** ERROR *****
2013-01-15 09:59:24 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 09:59:24 ***** ERROR ***** cause = Array to string conversion
2013-01-15 09:59:31 ***** ERROR ***** ERROR *****
2013-01-15 09:59:31 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 09:59:31 ***** ERROR ***** cause = Array to string conversion
2013-01-15 09:59:51 ***** ERROR ***** ERROR *****
2013-01-15 09:59:51 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 09:59:51 ***** ERROR ***** cause = Array to string conversion
2013-01-15 09:59:53 ***** ERROR ***** ERROR *****
2013-01-15 09:59:53 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 09:59:53 ***** ERROR ***** cause = Array to string conversion
2013-01-15 09:59:57 ***** ERROR ***** ERROR *****
2013-01-15 09:59:57 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 09:59:57 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:00 ***** ERROR ***** ERROR *****
2013-01-15 10:00:00 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:00 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:05 ***** ERROR ***** ERROR *****
2013-01-15 10:00:05 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:05 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:06 ***** ERROR ***** ERROR *****
2013-01-15 10:00:06 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:06 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:06 ***** ERROR ***** ERROR *****
2013-01-15 10:00:06 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:06 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:08 ***** ERROR ***** ERROR *****
2013-01-15 10:00:08 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:08 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:09 ***** ERROR ***** ERROR *****
2013-01-15 10:00:09 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:09 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:10 ***** ERROR ***** ERROR *****
2013-01-15 10:00:10 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:10 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:10 ***** ERROR ***** ERROR *****
2013-01-15 10:00:10 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:10 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:11 ***** ERROR ***** ERROR *****
2013-01-15 10:00:11 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:11 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:15 ***** ERROR ***** ERROR *****
2013-01-15 10:00:15 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:15 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:15 ***** ERROR ***** ERROR *****
2013-01-15 10:00:15 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:15 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:00:35 ***** ERROR ***** ERROR *****
2013-01-15 10:00:35 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:00:35 ***** ERROR ***** cause = Array to string conversion
2013-01-15 10:01:29 ***** ERROR ***** ERROR *****
2013-01-15 10:01:29 ***** ERROR ***** on file '/var/www/localhost/htdocs/projectorria/model/persistence/SqlElement.php' at line (1107)
2013-01-15 10:01:29 ***** ERROR ***** cause = Array to string conversion