What could this possibly mean ?

When the controller started the exceptions were not there, but apperaed 2 days after the start.

These logs  are not their during system start but develop therafter. Related event is some APs (randomly) which are up on network but cannot be adopted in Omada System and revert to standalone mode. The AP not getting adopted problem is fixed by manually rebooting the AP (PoE power down and up cycle) and Aps which go down are very random and not a fixed set of APs

System Config: Omada 5.9.31 on Rocky Linux 8.8, Intel Atom Dual Core hardware with 4G RAM and 64 GB SSD (software RAID-1 configuration)