PHP Errors when running under multisite

This issue was turning me crazy until I did a grep from the server and located the source of failure coming from your plugin. Let me show you:
When the plugin is activated under multisite, and running with WP 3.8.1, PHP >=5.4 and MySQL >=5.5, PHP is logging a lot of errors whenever one visitor hits ANY of the websites in the multisite, in the folder wp-admin:

[23-Mar-2014 03:51:11 UTC] Error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND meta_key = '_ready_options'' at line 1 de la base de datos de WordPress para la consulta SELECT meta_value FROM wp_postmeta WHERE post_id =  AND meta_key = '_ready_options' realizada por do_action('wp_ajax_refreshPreview'), call_user_func_array, handleControllerPrt->refreshPreview, optionsPrt->getPostMeta, optionsModelPrt->getPostMeta
[23-Mar-2014 03:51:18 UTC] Error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND meta_key = '_ready_options'' at line 1 de la base de datos de WordPress para la consulta SELECT meta_value FROM wp_postmeta WHERE post_id =  AND meta_key = '_ready_options' realizada por do_action('wp_ajax_refreshPreview'), call_user_func_array, handleControllerPrt->refreshPreview, optionsPrt->getPostMeta, optionsModelPrt->getPostMeta
[23-Mar-2014 03:54:15 UTC] Error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND meta_key = '_ready_options'' at line 1 de la base de datos de WordPress para la consulta SELECT meta_value FROM wp_postmeta WHERE post_id =  AND meta_key = '_ready_options' realizada por do_action('wp_ajax_refreshPreview'), call_user_func_array, handleControllerPrt->refreshPreview, optionsPrt->getPostMeta, optionsModelPrt->getPostMeta
[23-Mar-2014 03:55:41 UTC] Error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND meta_key = '_ready_options'' at line 1 de la base de datos de WordPress para la consulta SELECT meta_value FROM wp_postmeta WHERE post_id =  AND meta_key = '_ready_options' realizada por do_action('wp_ajax_refreshPreview'), call_user_func_array, handleControllerPrt->refreshPreview, optionsPrt->getPostMeta, optionsModelPrt->getPostMeta

And that’s just a sample from a 78 MB error log.

This is annoying because even if you use a small price list in only one site, every hit to any page in any site in that multisite will trigger this error. Also, all the sites in that multisite are browsing slowly, even if they dont use the plugin and the plugin is NOT network activated. Evidently is related to SMTHG tied to Ajax, but I learnt from grepping all the files in my system that the only one using references to “handleControllerPrt” is your plugin, specifically here:

/home/account/public_html/wp-content/plugins/pricing-table-ready/modules/handle/controller.php, line 2:
class handleControllerPrt extends controllerPrt {

So, I deactivated the plugin and the entire thing went back to normal. The sites started working speedy again and the php errors never came back.
I just switched to another plugin, but I wanted to let you know there is something buggy in there.

Hope it helps. Best regards!

https://wordpress.org/plugins/pricing-table-ready/