Using the new fatal handler introduced in [44962], an email is sent to the admin when a fatal error occurs. This email includes a secret link to enter recovery mode. When clicked, the link will be validated and on success a cookie will be placed on the client, enabling recovery mode for that user. This functionality is executed early before plugins and themes are loaded, in order to be unaffected by potential fatal errors these might be causing.
When in recovery mode, broken plugins and themes will be paused for that client, so that they are able to access the admin backend despite of these errors. They are notified about the broken extensions and the errors caused, and can then decide whether they would like to temporarily deactivate the extension or fix the problem and resume the extension.
A link in the admin bar allows the client to exit recovery mode.
Props timothyblynjacobs, afragen, flixos90, nerrad, miss_jwo, schlessera, spacedmonkey, swissspidy.
Fixes#46130, #44458.
Built from https://develop.svn.wordpress.org/trunk@44973
git-svn-id: http://core.svn.wordpress.org/trunk@44804 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This changeset introduces a `WP_Fatal_Error_Handler` class that detects fatal errors and displays a more user-friendly message about the site experiencing technical difficulties.
Websites that have custom requirements in that regard can implement their own fatal error handler by adding a `fatal-error-handler.php` drop-in that returns the handler instance to use, which must be based on a class that inherits `WP_Fatal_Error_Handler`. That handler will then be used in place of the default one. Alternatively, the fatal error handler feature can be completely disable through a constant `WP_DISABLE_FATAL_ERROR_HANDLER`.
Websites that would like to modify specifically the error template displayed in the frontend can add a `php-error.php` drop-in that works similarly to the existing `db-error.php` drop-in. For more granular customization, the fatal error handler also includes new filters `wp_should_handle_php_error`, `wp_php_error_message` and `wp_php_error_args`.
Props afragen, bradleyt, flixos90, ocean90, schlessera, SergeyBiryukov, spacedmonkey, timothyblynjacobs.
See #46130, #44458.
Built from https://develop.svn.wordpress.org/trunk@44962
git-svn-id: http://core.svn.wordpress.org/trunk@44793 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Due to the high number of follow-up tickets and associated security concerns, it was decided to reschedule the fatal error recovery feature for WordPress 5.2, in order to address these issues properly. The feature will continue to be developed, with iterations being merged into trunk early in the 5.2 release cycle.
Fixes#46141. See #44458, #45932, #45940, #46038, #46047, #46068.
Built from https://develop.svn.wordpress.org/trunk@44717
git-svn-id: http://core.svn.wordpress.org/trunk@44548 1a063a9b-81f0-0310-95a4-ce76da25c4cd
The `WP_Shutdown_Handler` name plus related function names were premature when originally committed, as there can be multiple shutdown handlers in PHP, and WordPress makes use of that feature. This changeset modifies the name to a more appropriate `WP_Fatal_Error_Handler`, and related to that changes the following names:
* The drop-in to override the handler is now called `fatal-error-handler.php`.
* The internal function `wp_register_premature_shutdown_handler` is now called `wp_register_fatal_error_handler()`.
In addition to these naming changes, a new constant `WP_DISABLE_FATAL_ERROR_HANDLER` is introduced that can be set in `wp-config.php` to entirely disable the fatal error handler. That constant's value is and should be accessed indirectly via a new `wp_is_fatal_error_handler_enabled()` function and is filterable via a new `wp_fatal_error_handler_enabled` hook. Note that disabling the fatal error handler will skip the new functionality entirely, including the potentially used `fatal-error-handler.php` drop-in.
The new set of constant, filter and function provide for an easier-to-use mechanism to disable the fatal error handler altogether, rather than requiring developers to implement a drop-in for purely that purpose.
Props afragen, flixos90, joyously, knutsp, markjaquith, ocean90, schlessera, spacedmonkey.
Fixes#46047. See #44458.
Built from https://develop.svn.wordpress.org/trunk@44674
git-svn-id: http://core.svn.wordpress.org/trunk@44505 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This changeset introduces a `WP_Shutdown_Handler` class that detects fatal errors and which extension (plugin or theme) causes them. Such an error is then recorded, and an error message is displayed. Subsequently, in certain protected areas, for example the admin, the broken extension will be paused, ensuring that the website is still usable in the respective area. The major benefit is that this mechanism allows site owners to still log in to their website, to fix the problem by either disabling the extension or solving the bug and then resuming the extension.
Extensions are only paused in certain designated areas. The frontend for example stays unaffected, as it is impossible to know what pausing the extension would cause to be missing, so it might be preferrable to clearly see that the website is temporarily not accessible instead.
The fatal error recovery is especially important in scope of encouraging the switch to a maintained PHP version, as not necessarily every WordPress extension is compatible with all PHP versions. If problems occur now, non-technical site owners that do not have immediate access to the codebase are not locked out of their site and can at least temporarily solve the problem quickly.
Websites that have custom requirements in that regard can implement their own shutdown handler by adding a `shutdown-handler.php` drop-in that returns the handler instance to use, which must be based on a class that inherits `WP_Shutdown_Handler`. That handler will then be used in place of the default one.
Websites that would like to modify specifically the error template displayed in the frontend can add a `php-error.php` drop-in that works similarly to the existing `db-error.php` drop-in.
Props afragen, bradleyt, flixos90, ocean90, schlessera, SergeyBiryukov, spacedmonkey.
Fixes#44458.
Built from https://develop.svn.wordpress.org/trunk@44524
git-svn-id: http://core.svn.wordpress.org/trunk@44355 1a063a9b-81f0-0310-95a4-ce76da25c4cd
John Blackbourn
Sergey Biryukov
Felix Arntz