wp-admin/includes/class-wp-automatic-updater.php:1761Performs a loopback request to check for potential fatal errors.
boolOne hook fires while WP_Automatic_Updater::has_fatal_error() runs, in this order:
Filters whether SSL should be verified for local HTTP API requests.
protected function has_fatal_error() { global $upgrading; $maintenance_file = ABSPATH . '.maintenance'; if ( ! file_exists( $maintenance_file ) ) { return false; } require $maintenance_file; if ( ! is_int( $upgrading ) ) { return false; } $scrape_key = md5( $upgrading ); $scrape_nonce = (string) $upgrading; $transient = 'scrape_key_' . $scrape_key; set_transient( $transient, $scrape_nonce, 30 ); $cookies = wp_unslash( $_COOKIE ); $scrape_params = array( 'wp_scrape_key' => $scrape_key, 'wp_scrape_nonce' => $scrape_nonce, ); $headers = array( 'Cache-Control' => 'no-cache', ); // Include Basic auth in the loopback request. if ( isset( $_SERVER['PHP_AUTH_USER'] ) && isset( $_SERVER['PHP_AUTH_PW'] ) ) { $headers['Authorization'] = 'Basic ' . base64_encode( wp_unslash( $_SERVER['PHP_AUTH_USER'] ) . ':' . wp_unslash( $_SERVER['PHP_AUTH_PW'] ) ); } // Time to wait for loopback request to finish. $timeout = 50; // 50 seconds. $is_debug = WP_DEBUG && WP_DEBUG_LOG; if ( $is_debug ) { error_log( ' Scraping home page...' ); } $needle_start = "###### wp_scraping_result_start:$scrape_key ######"; $needle_end = "###### wp_scraping_result_end:$scrape_key ######"; $url = add_query_arg( $scrape_params, home_url( '/' ) ); /** This filter is documented in wp-includes/class-wp-http-streams.php */ $sslverify = apply_filters( 'https_local_ssl_verify', false, $url ); $response = wp_remote_get( $url, compact( 'cookies', 'headers', 'timeout', 'sslverify' ) ); if ( is_wp_error( $response ) ) { if ( $is_debug ) { error_log( 'Loopback request failed: ' . $response->get_error_message() ); } return true; } // If this outputs `true` in the log, it means there were no fatal errors detected. if ( $is_debug ) { error_log( var_export( substr( $response['body'], strpos( $response['body'], '###### wp_scraping_result_start:' ) ), true ) ); } $body = wp_remote_retrieve_body( $response ); $scrape_result_position = strpos( $body, $needle_start ); $result = null; if ( false !== $scrape_result_position ) { $error_output = substr( $body, $scrape_result_position + strlen( $needle_start ) ); $error_output = substr( $error_output, 0, strpos( $error_output, $needle_end ) ); $result = json_decode( trim( $error_output ), true ); } delete_transient( $transient ); // Only fatal errors will result in a 'type' key. return isset( $result['type'] ); }Introduced in 6.6.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-automatic-updater.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.