You must set the highest priority for the core switch to prevent disputes over who will be the root of the topology.
It's a good idea to review the concepts of STP.
Hi Alemabrahao,
Thanks for more info, however, i has been check each access switch have the rstp root via core switch with priority 4096 which is correct path. not sure why still getting stp high rate, or i have to adjust priority to 0? even those root switch is already core switch. I also review the physical cable that might be suspected connection loop and I'm sure now that our network is loop free but still getting those alerts and sometimes no alert.
This is looking like a network loop, maybe it's better to review the LACP settings.
And always It's a good idea t set the highest priority (0) on the root switch.
RSTP topology changes are generated when a non edge port comes up.
If you are using the default trunk native vlan 1 configuration for all your access ports you could be generating a load of TCN's.
Please configure all ports that go to endpoints as access ports. Meraki software enables edge port / portfast automatically on access ports. Edge ports do not generate TCN's when they come up.
If this is not the case then there must be a part of the L2 domain in your network that actually does have unstable STP topology. Make sure you really check out the entire network.