Gateway: could not handle packet

I have a Kerlink iFemtocell gateway. The lora-gateway-bridge program is running on the gateway itself. But when a device is trying to join I get the following error.

time=“2018-10-22T08:21:11Z” level=error msg=“gateway: could not handle packet” addr=“127.0.0.1:54352” data_base64=Av29BXJ2/wA5AwSoAH19 error=“invalid character ‘\x00’ looking for beginning of value”

The version of the binary is 2.6. I have tried with v2_json and protobuf marshaller. Any suggestions how to fix this?

time="2018-10-22T08:20:19Z" level=info msg="starting LoRa Gateway Bridge" docs="https://www.loraserver.io/lora-gateway-bridge/" version=2.6.0
time="2018-10-22T08:20:19Z" level=info msg="gateway: starting gateway udp listener" addr="0.0.0.0:1700"
time="2018-10-22T08:20:19Z" level=info msg="mqtt: connected to mqtt broker"
time="2018-10-22T08:20:53Z" level=info msg="mqtt: subscribing to topic" qos=0 topic=gateway/7276ff00390304a8/tx
time="2018-10-22T08:20:53Z" level=info msg="mqtt: subscribing to topic" qos=0 topic=gateway/7276ff00390304a8/config
time="2018-10-22T08:21:02Z" level=info msg="mqtt: publishing message" qos=0 topic=gateway/7276ff00390304a8/rx
time="2018-10-22T08:21:03Z" level=info msg="mqtt: downlink frame received" topic=gateway/7276ff00390304a8/tx
time="2018-10-22T08:21:07Z" level=error msg="gateway: could not handle packet" addr="127.0.0.1:54352" data_base64=At6XBXJ2/wA5AwSoAH19 error="invalid character '\\x00' looking for beginning of value"
time="2018-10-22T08:21:10Z" level=info msg="mqtt: publishing message" qos=0 topic=gateway/7276ff00390304a8/rx
time="2018-10-22T08:21:11Z" level=info msg="mqtt: downlink frame received" topic=gateway/7276ff00390304a8/tx
time="2018-10-22T08:21:11Z" level=error msg="gateway: could not handle packet" addr="127.0.0.1:54352" data_base64=Av29BXJ2/wA5AwSoAH19 error="invalid character '\\x00' looking for beginning of value"

Hello do you fix the problem?

Have you tried the package from https://www.loraserver.io/lora-gateway-bridge/gateway/kerlink/?