Failed to set up demuxing for m-section

Sometimes I get this error and wonder if you have some ideas on how to troubleshoot it. Everything went well until this point and multiple other audio channels connected without a problem.

+00:00 ERR:"\"newConsumer\" request failed"
__Error: Failed to execute 'setRemoteDescription' on 'RTCPeerConnection': Failed to set remote offer sdp: Failed to set up demuxing for m-section with mid='8'.

This was the incoming request:

{
 "id": 2791747,
 "acks": {},
 "request": true,
 "method": "newConsumer",
 "data": {
   "uuid": "3c8e397f4d3549d988a6c76cbccd8821",
   "producerId": "ef8d7a17-1fd0-45a7-b0ef-3abaf4b76021",
   "id": "91d410b9-73c5-40ef-b71b-0389445078ce",
   "kind": "audio",
   "rtpParameters": {
     "codecs": {
       "0": {
         "mimeType": "audio/opus",
         "payloadType": 100,
         "clockRate": 48000,
         "channels": 2,
         "parameters": {
           "minptime": 10,
           "useinbandfec": 1,
           "sprop-stereo": 1,
           "usedtx": 1
         }
       }
     },
     "mid": "8"
   },
   "type": "simple",
   "producerPaused": false
 }
}

Thanks!