Err: try to send an unregistered frame

After I create a simulated drone, an error occurs: [] try to send an unregistered frame!
I do remember I registered once when I installed sphinx yesterday, maybe I need to log in every time I use it? But I cannot find where to log in

This error can sometimes appear because of synchronization issues while sending video frames to the firmware (basically, sphinx tries to send a frame to the firmware, but the firmware is not ready yet). It would only be problematic if it repeats itself. Otherwise, you can safely ignore it.

Thank you