Merak switch loses internet from Core switch

[kYutobi]

We have a 2 Cisco 2960's stacked and uplinked the port 24 on the Meraki switch. Every so often randomly we lose connectivity to whatever is plugged into switch. (phones, ap's, etc.) Devices stay powered on but are not online. When I look at event logs I get this

Core switch has priority of 1 and when i check that stack goes down then back up. Anyone experience this? 

[PhilipDAth]

First make sure errdisable recovery is enabled.

errdisable recovery cause all

errdisable recovery interval 30

Next change the 2960's to using mst.

spanning-tree mode mst

It is very important that both ends of the trunk have the same native vlan.  To keep life simple, I would leave the native vlan for the trunks as vlan1.

[PhilipDAth]

Also make sure your Meraki switch is running 9.32.