Update Piwik today to 2.12.0 (automatic update) - now, tracking is not working anymore but this error appears instead:
[Tue Mar 24 21:31:25 2015] [error] PHP Fatal error: Call to undefined method Piwik\\IP::isIPv4() in [PATH]/plugins/IPv6Usage/IPv6Usage.php on line 96
There are no new entries @ p_log_visit anymore since the update. Do you have any idea how to get Piwik back to work?
In addition (but not so important at the moment): before the update, when going to “All Websites”, at the top-right there was something like “You have installed Piwik x. xx” or “A new version is available”. It is gone as well. Was it intentional or is this an error as well?