When a drop-in (such as `advanced-cache.php`) contains a PHP error, additional PHP errors are caused when displaying the error protection screen because `load_default_textdomain()` and `WP_Error` are not yet available.
Though recovery mode is not supported for `mu-plugins` and drop-ins, fatal error protection is. This change ensures the error screen is displayed when a fatal error is encountered within a drop-in and not a white screen.
Props TimothyBlynJacobs, spacedmonkey, daxelrod.
Fixes#47265.
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When recovery mode is triggered before the site’s locale has been initialized, the message displayed to the user and the email sent to the site administrator with the recovery mode link are always rendered in `en_US`. This change ensures the site’s locale is used even when an error happens early in the loading process.
Reviewed by swissspidy, SergeyBiryukov, and desrosj.
Props wolly, TimothyBlynJacobs, fierevere.
Fixes#47093.
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This ensures that at least for the admin, which is more predictable than the frontend, the user-friendlier error notice from the fatal error handler still shows if a runtime fatal error happens within the page generation process.
Props axaak.
Fixes#46811.
Built from https://develop.svn.wordpress.org/trunk@45210
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Prior to this change, resuming or activating a plugin or theme that is still broken would result in a redirect loop if in recovery mode. If outside recovery mode, it would cause the error template to be displayed.
Furthermore this applies to breaking a plugin or theme when editing from the backend.
Props aandrewdixon, azaozz, dhanukanuwan, henrywright, ocean90, ohiosierra, PandelisZ, xkon.
Fixes#46045, #46751.
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If a fatal error occurs midway through a page load, or in a REST API request, it still needs to be handled internally for the recovery mode, but the custom message may conflict with already rendered output, e.g. by displaying HTML markup in an XML or JSON request.
Props spacedmonkey, flixos90, TimothyBlynJacobs.
Fixes#45989. See #44458.
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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.
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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.
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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
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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
Sergey Biryukov
desrosj
Felix Arntz