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 .\)