Once the DST occured at 2:00AM BlueIris started triggering repeated Onvif error 8000ffff on my 5 Hikvision Cameras. I use direct to disk recording and rely on the cameras to trigger BI to record. There are recordings prior to 2:00PM, nothing after. I am currently on V 5.8.7.11 but tried 5.8.8.3 and 5.8.8.2 without success. When I do an inspect I get the following results.

Opening 192.168.2.236 port 80...
HTTP Get / request...
OK
ONVIF GetSystemDateAndTime
2024-03-10T21:40:45.000Z
Requesting device information...
Manufacturer: HIKVISION
Model: DS-2CD2387G2P-LSU/SL
FirmwareVersion: V5.7.11
GetCapabilities...
Querying services
Has Search services: /onvif/SearchRecording
Has Imaging services: /onvif/Imaging
Has media services: /onvif/Media
Has RTP_RTSP_TCP, requesting profiles
profile token Profile_1
profile name mainStream
profile source is VideoSource_1
profile source config is VideoSourceToken
profile token Profile_2
profile name subStream
profile source is VideoSource_1
profile source config is VideoSourceToken
requesting URI for profile Profile_1
RTSP URI: /Streaming/Channels/101?transportmode=unicast&profile=Profile_1
requesting URI for profile Profile_2
RTSP URI: /Streaming/Channels/102?transportmode=unicast&profile=Profile_2
Has Event services: /onvif/Events
Has WSPullPointSupport
RelayOutputs: 1
RelayOutput: AlarmOut_0/Monostable/closed
InputConnectors: 1
Has Device IO services: /onvif/DeviceIO
AudioOutputs: 1
Done

I had the same multiple Onvif "Events: Request 8000ffff" at exactly 3am, on most but not all cameras, but recordings were not impacted.
BI 5.8.7.11 and cpai 2.5.6

I found a November post in IP Cam Talk referring to an issue with Onvif 8000ffff errors when DST ended. Seems there was a BI bug.

2:00am is also when Blue Iris performs its daily database maintenance unless otherwise changed to a different schedule.

Could be related.

Just now, ONVIF error 8000ffff ceased without me changing anything. From DST change at 2:00AM until now ONVIF connect to the hikvision cameras would not authenticate, and now, it does. I am at a loss to explain but it seems to have something to do with the DST change.