What is vlan flapping

Am facing the problem which is vlan flapping
Some packet dropped due to this issue. Please suggest

Check if STP port fast is enabled on access ports.

Also can you send the topology diagram ?

Please share more information on this what log message appears and how its flapping.

Message will be default vlan mismatch.

Might be some loop or broadcast packet will be in same Vlan.

To avoid that we can configure swicthport protect & spanning tree guard root command on access point to point port.