I have recently upgraded my O/S to OpenSuse Leap 15.0 and that installed PHP7 and Zend 3.2.0. I use bacula for backups and have webacula as a browser front end. I had some problems even getting this to work but eventually found ways around the problems but then I was getting two messages which seem to indicate bugs in the Zend framework. I am going to post separate reports for each.
This one is in Cache\Backend.php. The message is about each() being deprecated and on line 79 this is the case. Changing it to a foreach statement corrects the error.