There is no data for this report. Real time shows visits. (1 reply)

One of my Piwik installations is not working for some time (since April), despite updating it with whenever a new release would be published. I use it for multiple small sites, and while not my top priority, I still wonder about how to fix it. I do log PHP errors, and here is what I have:

[03-Jul-2014 04:25:43 America/New_York] PHP Fatal error: Class 'Piwik\Plugin\ControllerAdmin' not found in /path/piwik.php on line 53
[03-Jul-2014 08:29:16 UTC] PHP Fatal error: Class 'DeviceDetector\DeviceDetector' not found in /path/core/DeviceDetectorFactory.php on line 29
[03-Jul-2014 08:39:21 UTC] PHP Fatal error: Class 'DeviceDetector\DeviceDetector' not found in /path/core/DeviceDetectorFactory.php on line 29
[03-Jul-2014 09:09:45 UTC] PHP Fatal error: Class 'DeviceDetector\DeviceDetector' not found in /path/core/DeviceDetectorFactory.php on line 29
[16-Jul-2014 20:38:55 UTC] PHP Parse error: syntax error, unexpected $end, expecting T_FUNCTION in /path/core/Common.php on line 496
[16-Jul-2014 20:40:27 UTC] PHP Fatal error: Class 'Piwik\Url' not found in /path/core/Config.php on line 250

What I find interesting here is that Real Time visitors section reports visits and pageviews, but all else is empty and says "There is no data for this report." Graph is at zero as well. This tels me that the software is still registering visits, but reporting is broken.

Where should I look first?

Thanks