I couldn’t find a similar topic that would have answered my question.

my question is what is the UPLINK_FCNT_RETRANSMISSION error, what is the cause of that and can it be fixed?

Could these system-generated error messages be added to the chirpstack document, then it would be easier to debug payload errors.

Thank you

The same uplink frame counter was retransmitted by the device - meaning the frame counter in the message did not increment.

This could be a couple things (more possibilities, but two I have encountered):

  • For confirmed messages, the uplink may have arrive at the Network Server and the downlink may have not gotten back to the device, therefore the device would retry a message that was already received by the Network Server and would be rejected.
  • For unconfirmed messages, the uplink was resent with the same frame counter value