When viewing the PHP Extension page in Zend Server (Configuration > PHP), one of the extensions shows an orange "Warning" status and has the message "Warning: The extension <extension_name> is not loaded."
Zend Server 6
Check the apache error logs for further error messages. The location of the apache logs will vary depending on the operating system and the apache configuration. The following example was found in the Apache logs in RHEL 6.
In the case of a missing library, use the distribution's package management tools to verify which package should provide the file. For many files it is possible to reinstall the package without side effects. If there is any doubt, please contact the support team for verification.
Continuing with the RHEL 6 example, the following correctly installs the missing library.
In Linux installations, Zend Server consists of many packages. If one of the files is removed after installation, reinstalling the package will put the file back in the proper location.