未能与站点联系来检查致命错误，因此PHP修改已被回滚。您需要采用其他方式（如SFTP）上传您修改的PHP文件

如果在WordPress后台主题编辑中修改模板php文件，点击更新文件时提示“未能与站点联系来检查致命错误，因此PHP修改已被回滚。您需要采用其他方式（如SFTP）上传您修改的PHP文件”。

这个错误提示是 WordPress 4.9 之后添加的功能，检查 WP 文件编辑器中是否有PHP错误，以防止网站因修改模板文件而崩溃。

有人说是WP的BUG，也有人说和服务器主机环境配置有关，也有人说是主题中有不规范的代码或者是某些插件会影响编辑模板，众说不一，不管了。

如果不准备通过FTP替换修改模板文件，可以通过修改WordPress程序文件，删除这个代码检查功能。

以WP5.4为例，打开wp-admin/includes/file.php程序文件，删除505-616行的如下代码：

if ( $is_active && 'php' === $extension ) {
  		$scrape_key   = md5( rand() );
 		$transient    = 'scrape_key_' . $scrape_key;
 		$scrape_nonce = strval( rand() );
 		// It shouldn't take more than 60 seconds to make the two loopback requests.
 		set_transient( $transient, $scrape_nonce, 60 );
  		$cookies       = wp_unslash( $_COOKIE );
 		$scrape_params = array(
 			'wp_scrape_key'   => $scrape_key,
 			'wp_scrape_nonce' => $scrape_nonce,
 		);
 		$headers       = array(
 			'Cache-Control' => 'no-cache',
 		);
  		/** This filter is documented in wp-includes/class-wp-http-streams.php */
 		$sslverify = apply_filters( 'https_local_ssl_verify', false );
  		// Include Basic auth in loopback requests.
 		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'] ) );
 		}
  		// Make sure PHP process doesn't die before loopback requests complete.
 		set_time_limit( 300 );
  		// Time to wait for loopback requests to finish.
 		$timeout = 100;
  		$needle_start = "###### wp_scraping_result_start:$scrape_key ######";
 		$needle_end   = "###### wp_scraping_result_end:$scrape_key ######";
  		// Attempt loopback request to editor to see if user just whitescreened themselves.
 		if ( $plugin ) {
 			$url = add_query_arg( compact( 'plugin', 'file' ), admin_url( 'plugin-editor.php' ) );
 		} elseif ( isset( $stylesheet ) ) {
 			$url = add_query_arg(
 				array(
 					'theme' => $stylesheet,
 					'file'  => $file,
 				),
 				admin_url( 'theme-editor.php' )
 			);
 		} else {
 			$url = admin_url();
 		}
 		$url                    = add_query_arg( $scrape_params, $url );
 		$r                      = wp_remote_get( $url, compact( 'cookies', 'headers', 'timeout', 'sslverify' ) );
 		$body                   = wp_remote_retrieve_body( $r );
 		$scrape_result_position = strpos( $body, $needle_start );
  		$loopback_request_failure = array(
 			'code'    => 'loopback_request_failed',
 			'message' => __( 'Unable to communicate back with site to check for fatal errors, so the PHP change was reverted. You will need to upload your PHP file change by some other means, such as by using SFTP.' ),
 		);
 		$json_parse_failure       = array(
 			'code' => 'json_parse_error',
 		);
  		$result = null;
 		if ( false === $scrape_result_position ) {
 			$result = $loopback_request_failure;
 		} else {
 			$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 );
 			if ( empty( $result ) ) {
 				$result = $json_parse_failure;
 			}
 		}
  		// Try making request to homepage as well to see if visitors have been whitescreened.
 		if ( true === $result ) {
 			$url                    = home_url( '/' );
 			$url                    = add_query_arg( $scrape_params, $url );
 			$r                      = wp_remote_get( $url, compact( 'cookies', 'headers', 'timeout' ) );
 			$body                   = wp_remote_retrieve_body( $r );
 			$scrape_result_position = strpos( $body, $needle_start );
  			if ( false === $scrape_result_position ) {
 				$result = $loopback_request_failure;
 			} else {
 				$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 );
 				if ( empty( $result ) ) {
 					$result = $json_parse_failure;
 				}
 			}
 		}
  		delete_transient( $transient );
  		if ( true !== $result ) {
  			// Roll-back file change.
 			file_put_contents( $real_file, $previous_content );
 			if ( function_exists( 'opcache_invalidate' ) ) {
 				opcache_invalidate( $real_file, true );
 			}
  			if ( ! isset( $result['message'] ) ) {
 				$message = __( 'Something went wrong.' );
 			} else {
 				$message = $result['message'];
 				unset( $result['message'] );
 			}
 			return new WP_Error( 'php_error', $message, $result );
 		}
 	}