As you know, by default, Error Reporting is turned off. Enabling it will allow the message to display in the browser to give you an idea of where the problem may lie. To Enable Error Reporting in PrestaShop 1.5/1.6, please follow the steps below:
Step 1: Log into your hosting admin dashboard, control panel, SSH, or FTP client.
Step 2: Navigate to the PrestaShop 1.5/1.6 root folder.
Step 3: From there, navigate the path /config/defines.inc.php.
Step 4: Open up the defines.inc.php file in your preferred text editor.
Step 5: Find the line of code that reads define(_PS_MODE_DEV_ai??i??,false) This is line 28 by default as of PrestaShop 1.5.6 or line 29 by default as of PrestaShop 1.6.
Step 6: Change it to read define(_PS_MODE_DEV_,true);
Step 7: Save the defines.inc.php file back to the path, overwriting the existing file if needed.