http 500 eror on my prestashop

Sinds a week i have a http 500 error.....i have searched, but i have not enough knowledge to fix it...i got the error on the screen, but do not know what to do next. I hope someone can help me to correct the error.

Deprecated: Function get_magic_quotes_gpc() is deprecated in /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/config/defines.inc.php on line 129 Notice: tempnam(): file created in the system's temporary directory in /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/classes/PrestaShopAutoload.php on line 151 Fatal error: Uncaught Error: [] operator not supported for strings in /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/classes/db/DbQuery.php:70 Stack trace: #0 /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/classes/ObjectModel.php(203): DbQueryCore->from('shop', 'a') #1 /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/classes/shop/Shop.php(131): ObjectModelCore->__construct('1', NULL, NULL) #2 /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/classes/shop/Shop.php(392): ShopCore->__construct('1') #3 /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/config/config.inc.php(97): ShopCore::initialize() #4 /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/index.php(27): require('/mnt/web304/b2/...') #5 {main} thrown in /mnt/web304/b2/40/54448540/htdocs/Prestashop_01/classes/db/DbQuery.php on line 70