Some webhosters with opcache enabled might disable functions like this for security reasons. This should prevent foreign applications from deleting cached things.
Without ignoring this error piwik is unusable and will always shows the error message:
There is an error. Please report the message (...) Warning: Zend OPcache API is restricted by "restrict_api" configuration directive in /piwik/core/CacheFile.php on line 219
This call should treat the same way as opcache_reset() in core/Filesystem.php added with faffbd68b41a00a0e220138285094f517c07778d
Other functions which might be disabled:
Thanks for the pull request and fix. I've made couple other changes https://github.com/piwik/piwik/commit/3492bc2102c8f9f084a35861e3b4ceb28cbf4c26 and https://github.com/piwik/device-detector/commit/9a515ccc08e6a90ae117e346f3e8c705f66f0245