500 server error AH01071: Got error 'PHP message: PHP Fatal error

[hamccb]

hallo, 

sinds vandaag krijg ik de melding 500 server error , en ook de back office is niet meer te bereiken.

de hosting firma zegt dat dit het probleem is:

AH01071: Got error 'PHP message: PHP Fatal error: Uncaught exception 'PrestaShopException' with message 'Current theme unavailable "warehouse". Please check your theme directory name and permissions.' in /var/www/vhosts/support81.es/httpdocs/classes/controller/FrontController.php:259\nStack trace:\n#0 /var/www/vhosts/support81.es/httpdocs/init.php(31): FrontControllerCore->init()\n#1 /var/www/vhosts/support81.es/httpdocs/modules/paypal/express_checkout/ajax.php(28): include_once('/var/www/vhosts...')\n#2 {main}\n thrown in /var/www/vhosts/support81.es/httpdocs/classes/controller/FrontController.php on line 259\n'

 

iemand een idee hoe dit komt en hoe te verhelpen?