I installed APCu for a MediaWiki website but I get some nasty errors about the caching. I noticed that the version of APCu is not the same as the one reported by APC.

APCu APC version doesn't match

I verified the installed packages but nothing seems out of the ordinary:

[centos@status etc]$ yum list installed | grep apc
php-pecl-apcu.x86_64                  5.1.17-1.el7.remi.7.2          @remi-php72
php-pecl-apcu-bc.x86_64               1.0.4-1.el7.remi.7.2           @remi-php72

[centos@status etc]$ php -v
PHP 7.2.15 (cli) (built: Feb  5 2019 19:50:47) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.2.15, Copyright (c) 1999-2018, by Zend Technologies

What could cause APC reporting that the APCu version is older than the actual version?

I'm not sure if more information is needed, if so I'll update the question.


APC report the version of APCu used at build time, which may be lower than the version used at runtime. This is not an issue, as the internal ABI is stable.

BTW, the apcu_bc extension should be considered as deprecated, all applications should use the new APCU API. This extension was provided for compatibility with PHP 5 for legacy applications.

  • Thank you very much, this was very confusing. I am glad you dropped by. – HypeWolf Feb 19 at 1:25

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