Why PHP error types appear in your captures #
When Loupely captures a diagnostic session, the PHP error layer records every PHP error that fired on the page. The capture file and the diagnosis output classify these by type. Knowing what each type means tells you how urgent the error is and what it’s doing to your site.
Fatal Errors #
A fatal error is a PHP error so severe that PHP stops running the script entirely. The page doesn’t finish loading. On WordPress, this is what causes the White Screen of Death, the “critical error on this website” message, or a 500 Internal Server Error. Fatal Errors almost always require immediate attention because they take pages or the entire site offline. They typically appear in Loupely captures with the specific file path and line number where PHP stopped, which identifies the plugin or theme responsible. See White Screen of Death and 500 Internal Server Error for how to act on these.
Warnings #
A PHP warning is a non-fatal error: something went wrong, but PHP kept running. The page may still load. However, warnings are PHP telling you that the code did something it shouldn’t have: used a variable that doesn’t exist, called a function with the wrong type of argument, tried to open a file that isn’t there. Warnings that appear in your Loupely capture on every page load are worth investigating even when they aren’t currently breaking anything. When a PHP version upgrade happens, some warnings become Fatal Errors in the newer version. A capture with 40 warnings is a site waiting for its next PHP upgrade to break.
Notices #
A PHP notice is the lowest severity level: PHP noticed something that could be a problem but might also be normal behavior. Common notices include references to undefined array keys or undefined variables. Notices rarely indicate an active problem but can accumulate in large numbers and fill error logs quickly. In Loupely captures, a large number of notices from the same plugin often points to code that hasn’t been updated to use current PHP conventions.
Deprecation notices #
A deprecation notice is a specific type of notice that says: “this function or feature still works, but it will be removed in a future PHP version.” In Loupely captures, deprecation notices from plugins are worth noting before a PHP upgrade. Code that is currently producing deprecation notices will likely produce Fatal Errors after the next major PHP version bump. See PHP Version Conflict for how this plays out in practice.
Parse errors #
A parse error means PHP encountered code it couldn’t understand at all, usually a syntax error: a missing semicolon, an unclosed bracket, a typo in a function name. Parse errors are almost always fatal. They appear when someone has manually edited a PHP file (a plugin, a theme’s functions.php, or wp-config.php) and introduced a syntax mistake. Loupely captures the file path of the parse error, which identifies exactly which file needs to be fixed.