I have been using iManager 2.7.0 for over a year to manage my Access Rules on our BM 3.9 NW 6.5 SP7 server. I was able to log in to it yesterday and make an addition to the blocked list. However, this morning when I logged in to iManager|BorderManager|Access Rules|Object History Button|Select our BM Server|OK
I get: Either you have selected the wrong object or the migration is not done properly (Please run the fillattr manually )

I updated iManager on this server to 2.7.3 FTF4, no change, removed and reinstalled the BM-related plugins, no change. I tried the same procedure from a different NW server, also updating it to 2.7.3 FTF4, different error at the same place:
key configmanager.msg.deviceconfig.alertdevicenotfound not found in resources.volsc.SystemControllerResources

I have no idea what could have happened between yesterday and today to cause this error on a server that had been functioning normally for over a year. The ACL is still there and functioning, as I can see users being blocked from websites that were manually added to the deny lists. I just cannot edit these lists now. I can still access other iManager functions that are controlled by iManager plugins (general BM functions and proxy services), it seems to be something about the ACL itself. DSREPAIR didn't find any errors that seemed to be related to it. There are errors on the console when I am trying to access the ACL through iManager:

VCDNException::ErrorCode=Unable to read attribute value,ResourceBundle=resources
.application.sc.Resource,MessageKey=Unable to read attribute valueSource=NBMAclD

deviceConfig is null
Use config is complete
in The End tag of Use device
Current choosen device in USEDEVICEACL
Error messag is <script language='javascript1.3'>function goBack(){window.locati
on='/nps/servlet/webacc?NPService=fw.LaunchService&NPAction=Delegat e&delegate=bm
.acltask&launcher=fw.HomePage&lifecycle=Recreate&r epeatable=true'}</script>

Unfortunately, I cannot update to NW6.5 SP8 or BM 3.9SP2, my superiors refuse to allow any internet downtime whatsoever.
Does anyone have any idea what might have caused this, or something I might resolve it that I haven't already tried?