Notice: Undefined property: DOMDocument::$documentElement

Question

I recently re-opened an old (1 year) Symfony project and I am having an error on every page (I don't remember having this issue a year ago) :

[exception] 500 | Internal Server Error | Symfony\Component\Config\Exception\FileLoaderLoadException
/var/www/[...]/wdt.xml

ContextErrorException: Notice: Undefined property: DOMDocument::$documentElement

If I clear the cache, the error disappear but as soon as I edit and save a file, the error is showing up again. The project was using Symfony 2.8 and I updated to Symfony 3.2 but it didn't solve the issue.

I don't think the problem is related to the wdt.xml file and I think it might be related to my laptop config.

I don't really know where to start to investigate so any suggestion is welcome!

Edit 1 :
I am actually having the same problem with another project I created few days ago. The project don't use any additional bundles and I just created 5 entities and generated the MySQL database.

Edit 2 :
After some more researched, I decided to create a new Ubuntu VM and test a new Symfony project and it just work perfectly so it must be something to do with the configuration on my laptop.

Edit 3 :
After some more tests, here is what I get when I add a print_r($dom); in the file XmlUtils.php (vendor/symfony/symfony/src/Symfony/Component/Config/Util/XmlUtils.php) line 59 :

Ubuntu VM (no error) :

DOMDocument Object ( [doctype] => [implementation] => (object value omitted) [documentElement] => (object value omitted) [actualEncoding] => [encoding] => [xmlEncoding] => [standalone] => 1 [xmlStandalone] => 1 [version] => 1.0 [xmlVersion] => 1.0 [strictErrorChecking] => 1 [documentURI] => /var/www/my_project/web/ [config] => [formatOutput] => [validateOnParse] => 1 [resolveExternals] => [preserveWhiteSpace] => 1 [recover] => [substituteEntities] => [nodeName] => #document [nodeValue] => [nodeType] => 9 [parentNode] => [childNodes] => (object value omitted) [firstChild] => (object value omitted) [lastChild] => (object value omitted) [previousSibling] => [attributes] => [ownerDocument] => [namespaceURI] => [prefix] => [localName] => [baseURI] => /var/www/my_project/web/ [textContent] => %kernel.charset% %kernel.default_locale% )

Ubuntu laptop (error) :

DOMDocument Object ( [validateOnParse] => 1 [nodeName] => #document [nodeValue] => [nodeType] => 9 [parentNode] => [childNodes] => (object value omitted) [firstChild] => (object value omitted) [lastChild] => (object value omitted) [previousSibling] => [attributes] => [ownerDocument] => [namespaceURI] => [prefix] => [localName] => [baseURI] => /var/www/lab/symfony/booklib/web/ [textContent] => %kernel.charset% %kernel.default_locale% )

It looks like there is some missing information on my laptop...

So basically, the function $dom->loadXML doesn't return the same value on my laptop environment and inside the VM... any idea why?

Recurve

Answer 1

I have Ubuntu 16.04 installation with php7.0.15, and i fixed the error by just removing php-xdebug extension.

sudo apt-get purge php-xdebug

Krug

phpdismod xdebug && service php7.1-fpm restart and error gone for me. wery strange... – Dowery

purging xdebug fixed it for me, too – Vidal

Answer 2

In my case the error was triggered by the dom.so extension being loaded in two places. Removing one fixed the problem.

Steady

Thanks, this solution was for me the best – Discouragement

where to find dom.so in host cpanel???? – Spahi

Answer 3

I finally resolved the problem by uninstalling / reinstalling php7. I have no idea why I had this issue though...

Recurve

Answer 4

In my case the dom extension was enabled twice. Once in the dom.ini and also in the php.ini. I removed the extension=dom.so entry from the php.ini and reloaded the apache2 webserver.

Douville

Answer 5

This might be relevant: https://getcomposer.org/doc/articles/troubleshooting.md#xdebug-impact-on-composer

TLDR: Use COMPOSER_ALLOW_XDEBUG=1 if you are using xdebug with composer.

Pretty

Answer 6

This is very strange BUT try to change php extensions load order in php config. This solve my problem... move dom extension above or below in list

Dowery

For me similar solution has worked - I had dom extension in 2 places. I removed it from one and then it started working. 2nd one was probably ignored so extension order was most probably the problem. – Anson

Answer 7

Hi I also meet this problem. The way I resolve it is:

composer update

Hope that help some one.

Selfdevotion

Hi, It didn't solve my problem because it's not related to Symfony (I've done another test outside Symfony and I have the exact same error). – Recurve

Yes, It does. I already debug. At the beginning I thought because XML binary lib but It is not. When I update and it fixed my issue. – Selfdevotion

I had the same problem outside Symfony but maybe your issue was actually a different one. I tried the composer update solution but didn't work for me. – Recurve

Answer 8

Thank @pjehan. I had the same problem and I've lost a day. Finally, I did like you and it was successful. Just specify one thing: unistall PHP 7.0.x and PHP 7.1.3 intaller (stable version for PHP 7). The link of the version PHP 7 stable: http://php.net/downloads.php Thank you so much, @pjehan, you saved my life :D

Villalobos

You're welcome, I wish I could have found the exact problem and another way than just uninstall and reinstall but after spending 6 hours trying to find a solution, I just gave up and choose the easiest way to solve this problem. I am glad it helped you thought 😉 – Recurve

Answer 9

I solved the problem by disabling xdebug for the cli

Routh