Not really a problem for me, but possibly helpful to others trying to troubleshoot this issue. I have a camera with WiFi capability. I get this message when I connect to the camera, but nowhere else. Based on what I've read, it seems most likely to me that the upgrade has added new parameters to trigger the error message. I just got a S4 with 4.3, so I don't have any other experience with this phone. I never got this error on my S3.
Everything works fine, but I get the stupid message every time. I intend to disable. I hope this helps.