What does “XDEBUG NOT LOADED AS ZEND EXTENSION” warning means?

Question

Xdebug is loaded, but not loaded as a zend extension. What does it mean? How to resolve this problem?

Answer 1

Others have already explained that the error is because Xdebug is being loaded as a regular PHP module instead of as a Zend extension. You can use the wizard that Derick linked to or manually enter the line as Starx showed.

However, there is an issue that you may run into. The extensions_dir directive in php.ini currently only applies to PHP modules, not to Zend extensions. Therefore, you cannot use a common configuration like this:

[PHP]
extension_dir  = .\ext
extension      = php_memcache.dll
…
[zend]
zend_extension = php_xdebug-2.2.3-5.3-vc9-nts.dll

While PHP will correctly load php_memcache.dll from the ext sub-directory, it will not load php_xdebug-2.2.3-5.3-vc9-nts.dll and will throw the error Failed loading php_xdebug-2.2.3-5.3-vc9-nts.dll.

To fix this, you will need to either use an fully-qualified/absolute path such as:

zend_extension = C:\foobar\PHP\ext\php_xdebug-2.2.3-5.3-vc9-nts.dll

or a relative path such as these:

zend_extension = ext\php_xdebug-2.2.3-5.3-vc9-nts.dll
zend_extension = ..\phpexts\php_xdebug-2.2.3-5.3-vc9-nts.dll
zend_extension = \dev\phpexts\php_xdebug-2.2.3-5.3-vc9-nts.dll

(The wizard will return zend_extension=.\ext\php_xdebug-2.2.3-5.3-vc9-nts.dll which includes the directory but also a superfluous .\)

Answer 2

This error means that you used "extension=" to load Xdebug. That could be in your normal php.ini, or in a file called xdebug.ini that some distributions like to add. In any case, Xdebug needs to be loaded as a Zend extension for certain features such as single step debugging. As Xdebug is not meant to work as a normal extension, it might crash and burn too.

The syntax for loading Xdebug as Zend extension depends on PHP version and build. I would suggest you use http://xdebug.org/wizard.php to provide you with the correct lines.

Answer 3

If you end up here while trying to build xdebug, then it means you have built it as a "static" extension (not a zend one).

You can use configure --with-xdebug=shared to build it as a shared extension (dll/so; you should see a table showing that xdebug is now configured to be built as a shared extension instead of a static one) so it can be loaded as a zend extension afterward.

I don't know if you can make a static zend extension.

Also, note that running the full test suite of xdebug requires to not activate opcache (configure --disable-opcache --with-xdebug=shared)

Answer 4

If you want to activate zend*nts*.dll into you php.ini file on Windows servers, you must use zend_extension_ts directive instead of zend_extension

Example to load xdebug :

[XDeug]
zend_extension_ts="DRIVE:/PATH_TO_XDEBUG/php_xdebug.dll"
xdebug.show_local_vars=1
xdebug.default_enable=On

Note : the double quotes to your dll file

Hope that will helps someone :)

Answer 5

Make sure if it is configured to load correctly as a zend_extension. Inside php.ini add this line

zend_extension="/usr/local/php/modules/xdebug.so"