Title: Uncaught Error: Class ‘DOMDocument’ Last modified: December 22, 2016 --- # Uncaught Error: Class ‘DOMDocument’ * Resolved [Zach Malmgren](https://wordpress.org/support/users/zmalmgren/) * (@zmalmgren) * [9 years, 5 months ago](https://wordpress.org/support/topic/uncaught-error-class-domdocument/) * In the “Above The Fold Optimization” screen, on the “Critical CSS” tab, if I use the “Extract Full CSS” by selecting “Home Page (Index)” and clicking “Print”, I get a new window with the URL of “[https://www.planetscon.com/?extract-css=39bf18531a83fc138e3cfb5e2be27068&output=print”](https://www.planetscon.com/?extract-css=39bf18531a83fc138e3cfb5e2be27068&output=print”);. However, the page displays as normal. * In the error logs of the nGinx server I get the following: * ``` 2016/12/22 12:31:32 [error] 4158#4158: *805 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Error: Class 'DOMDocument' not found in /var/www/planetscon_com/public_html/wp-content/plugins/above-the-fold-optimization/includes/extract-full-css.class.php:92 Stack trace: #0 [internal function]: Abovethefold_ExtractFullCss->end_buffering('...', 9) #1 /var/www/planetscon_com/public_html/wp-includes/functions.php(3673): ob_end_flush() #2 /var/www/planetscon_com/public_html/wp-includes/class-wp-hook.php(298): wp_ob_end_flush_all('') #3 /var/www/planetscon_com/public_html/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters('', Array) #4 /var/www/planetscon_com/public_html/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #5 /var/www/planetscon_com/public_html/wp-includes/load.php(670): do_action('shutdown') #6 [internal function]: shutdown_action_hook() #7 {main} thrown in /var/www/planetscon_com/public_html/wp-content/plugins/above-the-fold-optimization/includes/extract-full-css.class.php on line 92" while reading upstream, client: , server: , request: "GET /?extract-css=39bf18531a83fc138e3cfb5e2be27068&output=download HTTP/2.0", upstream: "fastcgi://unix:/run/php/planetscon_com.sock:", host: "www.planetscon.com" ``` * I am running Ubuntu 16.04.1 LTS / nginx/1.10.0 (Ubuntu) / PHP 7.0.8-0ubuntu0.16.04.3( cli) ( NTS ) * Thank you, and please let me know what other information would be helpful. Viewing 2 replies - 1 through 2 (of 2 total) * Plugin Author [optimalisatie](https://wordpress.org/support/users/optimalisatie/) * (@optimalisatie) * [9 years, 5 months ago](https://wordpress.org/support/topic/uncaught-error-class-domdocument/#post-8582369) * Hi zmalmgren, * Thank you for reporting the problem! * The class `DOMDocument` should be available by default in PHP 7. * [http://php.net/manual/en/class.domdocument.php](http://php.net/manual/en/class.domdocument.php) * Regrettably, we are not able to help with (advanced) server configuration. * I did a quick search in Google and a fix may be provided in the following topic: * [http://stackoverflow.com/questions/35668702/php-7-domdocument-not-found](http://stackoverflow.com/questions/35668702/php-7-domdocument-not-found) * _[ [Signature moderated](http://codex.wordpress.org/Forum_Welcome#Signatures)]_ - This reply was modified 9 years, 5 months ago by [Jan Dembowski](https://wordpress.org/support/users/jdembowski/). * Thread Starter [Zach Malmgren](https://wordpress.org/support/users/zmalmgren/) * (@zmalmgren) * [9 years, 5 months ago](https://wordpress.org/support/topic/uncaught-error-class-domdocument/#post-8582562) * Jan, * Thank you for your help. I got it to work with the following: * ``` sudo apt-get install php-xml sudo service php7.0-fpm restart ``` * However, the page still threw an error “PHP message: PHP Fatal error: Uncaught Error: Call to undefined function mb_convert_encoding()”. So I had to add: * ``` sudo apt-get install php-mbstring sudo service php7.0-fpm restart ``` * Thanks again for your help! Viewing 2 replies - 1 through 2 (of 2 total) The topic ‘Uncaught Error: Class ‘DOMDocument’’ is closed to new replies. * ![](https://s.w.org/plugins/geopattern-icon/above-the-fold-optimization_fcfbf6. svg) * [Page Speed Optimization](https://wordpress.org/plugins/above-the-fold-optimization/) * [Frequently Asked Questions](https://wordpress.org/plugins/above-the-fold-optimization/#faq) * [Support Threads](https://wordpress.org/support/plugin/above-the-fold-optimization/) * [Active Topics](https://wordpress.org/support/plugin/above-the-fold-optimization/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/above-the-fold-optimization/unresolved/) * [Reviews](https://wordpress.org/support/plugin/above-the-fold-optimization/reviews/) ## Tags * [php-fpm](https://wordpress.org/support/topic-tag/php-fpm/) * 2 replies * 2 participants * Last reply from: [optimalisatie](https://wordpress.org/support/users/optimalisatie/) * Last activity: [9 years, 5 months ago](https://wordpress.org/support/topic/uncaught-error-class-domdocument/#post-8582369) * Status: resolved