I installed the PHP extension APC on the server but I get it not running. It gets not listed in phpinfo(). After activating the php error log I get the following error:

PHP Startup: Unable to load dynamic library '/var/www/vhosts/chroot/usr/lib64/php/modules/apcu.so: undefined symbol: php_pcre_exec in Unknown on line 0

I am using the following versions Ubuntu 14.04.3 / PHP 5.6.13 / Apache 2.4.7

The installation has been made with:

 sudo apt-get install php-apc

In phpinfo I don't see any extension for apc. I jsut see that the following files has been added "/etc/php5/apache2/conf.d/20-apcu.ini" which seems to get parsed in addition to php.ini and in the ini file is


The apcu.so file has been installed through apt-get and is in



any hints how this error "undefined symbol: php_pcre_exec" can be solved. Which additional libraries are missing?

1 Answer 1


Create a php info page

<?php phpinfo(); ?>

and then see if /etc/php5/apache2/conf.d/ is included here at

scan this dir for additional .ini files


also the file "/etc/php5/apache2/conf.d/20-apcu.ini" should be listed in the

Additional .ini files parsed

if not, you could move the ini file to that directory, or change the directory in the php.ini how-do-i-include-a-php-ini-file-in-another-php-ini-file

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .