IPS log - Error reading session data / failed to get sessiontbl data for session id

Hi community,

we found many of the following entries in the /log/ips.log without facing any service interruptions or performance issues.

XG450_WP02_SFOS 18.0.5 MR-5-Build586# tail /log/ips.log
[Sep 03 08:49:53 :25629]:Error reading session data,status -1
[Sep 03 08:49:53 :25629]:failed to get sessiontbl data for session id 1842 rev 34571 pkt_len 0 datalink_type 228 direction 0 daq_source 2 is_tcp 0 nseid 0 is_ssl_non_app_appdata 0, dropping packet
[Sep 03 08:49:53 :25629]:Error reading session data,status -1
[Sep 03 08:49:53 :25629]:failed to get sessiontbl data for session id 1842 rev 34571 pkt_len 0 datalink_type 228 direction 0 daq_source 2 is_tcp 0 nseid 0 is_ssl_non_app_appdata 0, dropping packet
[Sep 03 08:49:54 :25625]:Error reading session data,status -1
[Sep 03 08:49:54 :25625]:failed to get sessiontbl data for session id 1852 rev 41991 pkt_len 0 datalink_type 228 direction 0 daq_source 2 is_tcp 0 nseid 0 is_ssl_non_app_appdata 0, dropping packet
[Sep 03 08:49:54 :25625]:Error reading session data,status -1
[Sep 03 08:49:54 :25625]:failed to get sessiontbl data for session id 1852 rev 41991 pkt_len 0 datalink_type 228 direction 0 daq_source 2 is_tcp 0 nseid 0 is_ssl_non_app_appdata 0, dropping packet
[Sep 03 08:49:54 :25625]:Error reading session data,status -1
[Sep 03 08:49:54 :25625]:failed to get sessiontbl data for session id 1852 rev 41991 pkt_len 0 datalink_type 228 direction 0 daq_source 2 is_tcp 0 nseid 0 is_ssl_non_app_appdata 0, dropping packet

Is this a normal or expected behavior?

Does anyone have an explanation for this?

Thanks in advance.

Markus