Actually I have not logged to the admin last 24h. And since it is a shared hosting, I can not reboot the server.
I checked with the company, they said all the files seems OK.
Interesting part is all pages are working but I am getting this error for the homepage only. I tried to create a dummy order and succeded. But the homepage still give the error. I Think that is sthg with home page settings?
Looks like your site was hacked. Suggest you change all passwords related to FTP, cPanel, Root and any other site access methods. Disable all 3rd party FTP accounts.