I would like to point out that there have been talked on the PHP mailing list and here what someone have to say:
There this:
Source: http://www.mail-archive.com/php-general@lists.php.net/msg275173.html and http://www.mail-archive.com/php-general@lists.php.net/msg275174.html
Quote
Could you try to add a function_exists check to
libs/upgradephp/upgrade.php?
This at the function declaration of _json_encode:
if (!function_exists('_json_encode')) { function _json_encode($var, ...
And a extra } at the end.
This seemed to correct this fatal error on my side:
[02-Sep-2013 10:35:40 Europe/Paris] PHP Fatal error: Cannot redeclare
_json_encode() (previously declared in
/usr/local/lib/php/share/piwik/libs/upgradephp/upgrade.php:109) in
/usr/local/lib/php/share/piwik/libs/upgradephp/upgrade.php on line 109
I do not know what opcache has to do with it, although I suspect that
Piwik is calling itself a lot of times and that opcache is trailing
behind (or something like that).
There this:
Quote
This patch, together with upgrading to the latest OPcache from github
solved my segfaults and fatal errors.
Source: http://www.mail-archive.com/php-general@lists.php.net/msg275173.html and http://www.mail-archive.com/php-general@lists.php.net/msg275174.html