Long term, would probably be a good idea to fix the error in "/includes/classes/class.String.php"...
The file "/includes/classes/class.String.php" is not part of a stock Zen Cart installation... Any idea where this file came from?
The file "/includes/extra_configures/enable_error_logging.php" appears to be where error reporting is configured for debug files. If you want to exclude strict error reporting try changing lines 40-44:
Code:
/**
* Error reporting level to log
* Default: E_ALL ^E_NOTICE
*/
$errors_to_log = (version_compare(PHP_VERSION, 5.3, '>=') ? E_ALL & ~E_DEPRECATED & ~E_NOTICE : version_compare(PHP_VERSION, 5.4, '>=') ? E_ALL & ~E_DEPRECATED & ~E_NOTICE & ~E_STRICT : E_ALL & ~E_NOTICE);
Change the order around so when PHP 5.4 or greater is installed & ~E_STRICT is added (which should exclude strict errors from the logs if all goes well).
Code:
/**
* Error reporting level to log
* Default: E_ALL ^E_NOTICE
*/
$errors_to_log = (version_compare(PHP_VERSION, 5.4, '>=') ? E_ALL & ~E_DEPRECATED & ~E_NOTICE & ~E_STRICT : version_compare(PHP_VERSION, 5.3, '>=') ? E_ALL & ~E_DEPRECATED & ~E_NOTICE : E_ALL & ~E_NOTICE);
Note: there is also a copy at "/admin/includes/extra_configures/enable_error_logging.php" you may need to change if the error is being generated from the admin.