PHP Fatal error: Uncaught Error: Class 'DOMDocument' not found in /var/www/html/magento/vendor/mage

[CursedChico]

caner@vegan:/var/www/html/magento$ sudo php bin/magento setup:upgrade
PHP Fatal error:  Uncaught Error: Class 'DOMDocument' not found in /var/www/html/magento/vendor/magento/framework/Config/Dom.php:377
Stack trace:
#0 /var/www/html/magento/vendor/magento/framework/Config/Dom.php(109): Magento\Framework\Config\Dom->_initDom('<?xml version="...')
#1 /var/www/html/magento/vendor/magento/framework/ObjectManager/Config/Reader/Dom.php(70): Magento\Framework\Config\Dom->__construct('<?xml version="...', Object(Magento\Framework\App\Arguments\ValidationState), Array, 'xsi:type', NULL)
#2 /var/www/html/magento/vendor/magento/framework/Config/Reader/Filesystem.php(146): Magento\Framework\ObjectManager\Config\Reader\Dom->_createConfigMerger('Magento\\Framewo...', '<?xml version="...')
#3 /var/www/html/magento/vendor/magento/framework/Config/Reader/Filesystem.php(127): Magento\Framework\Config\Reader\Filesystem->_readFiles(Object(Magento\Framework\Config\FileIterator))
#4 /var/www/html/magento/vendor/magento/framework/App/ObjectManagerFactory.php(282): Magento\Framework\Config\Reader\Filesystem->read('prim in /var/www/html/magento/vendor/magento/framework/Config/Dom.php on line 377
caner@vegan:/var/www/html/magento$ 

when i try to install from beginning, i tried to do upgrade.

because i have

One or more indexers are invalid. Make sure your Magento cron job is running.

error

and only 

	Catalog Rule Product	Indexed rule/product association	
UPDATE ON SAVE
REINDEX REQUIRED
Sep 6, 2016, 2:53:15 PM

is reindex requiired.

SO i searched for this error and  upgrading was suggested.

magento official docs are so complicated and meaningless, i couldn nderstand anything.

I just want to add a plugin to magento.

[ipragmatech]

Hello CursedChico,

You need to install the DOM extension. You can do so on Debian / Ubuntu using:  

sudo apt-get install php5-dom

If you get conflicts between PHP 5 and PHP 5.3 packages, you could try to see if the php53-xml package exists instead.

Note Please check PHP version before your installation. If you are using PHP7 then follow this tutorial. 

and finally restart your apache.

[CursedChico]

When i do

caner@vegan:~$ sudo apt-get install php5-dom
[sudo] password for caner: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package php5-dom

 i got error

[ipragmatech]

Please run sudo apt-get update then install php5-dom.

make sure you are using php5.

[CursedChico]

YEs sir, i did it. After it

caner@vegan:~$ sudo apt-get install php5-xml
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package php5-xml
caner@vegan:~$ sudo apt-get install php5.6-xml
Reading package lists... Done
Building dependency tree       
Reading state information... Done
php5.6-xml is already the newest version (5.6.25-2+deb.sury.org~xenial+1).
0 upgraded, 0 newly installed, 0 to remove and 14 not upgraded.
caner@vegan:~$ 

i have 5.6 and 7 but i use 5.6 for magnto. with 7, i got errors because.

[niranjan2016]

Hi,

I am also in same exact situation and none of my command line tools are working. Any resolution found on this?

[ipragmatech]

Hello Niranjan,

Basically, Magento need php extension for the execution. So you must need to install the php extesion. Dom one of the php extension so install the php dom extension according to your version and make sure this is enable.

[MagentaB]

By installing two packages it will solve the issue,

sudo apt-get install php7.0-imap
sudo apt-get install php-xml

[Hackerthon]

I am also getting the same error....
I have installed php-xml, dom as well as php-imap, still getting the same error.

Fatal error: Uncaught Error: Class 'DOMDocument' not found in /var/www/html/shop/vendor/magento/framework/Config/Dom.php:384 Stack trace: #0 /var/www/html/shop/vendor/magento/framework/Config/Dom.php(115): Magento\Framework\Config\Dom->_initDom('<?xml version="...') #1 /var/www/html/shop/vendor/magento/framework/ObjectManager/Config/Reader/Dom.php(70): Magento\Framework\Config\Dom->__construct('<?xml version="...', Object(Magento\Framework\App\Arguments\ValidationState), Array, 'xsi:type', NULL) #2 /var/www/html/shop/vendor/magento/framework/Config/Reader/Filesystem.php(149): Magento\Framework\ObjectManager\Config\Reader\Dom->_createConfigMerger('Magento\\Framewo...', '<?xml version="...') #3 /var/www/html/shop/vendor/magento/framework/Config/Reader/Filesystem.php(130): Magento\Framework\Config\Reader\Filesystem->_readFiles(Object(Magento\Framework\Config\FileIterator)) #4 /var/www/html/shop/vendor/magento/framework/App/ObjectManagerFactory.php(275): Magento\Framework\Config\Reader\Filesystem->read('primary') #5 /var/www/ in /var/www/html/shop/vendor/magento/framework/Config/Dom.php on line 384