Invalid protocol version

I use UDP client tool to send UDP packet to LoRa Gateway Bridge port. but I get this error in the log

time=“2018-10-05T16:44:46+03:00” level=error msg=“gateway: could not handle packet: gateway: invalid protocol version”

This is my data: 212012345678{“stat”:{“time”:“2014-01-12 08:59:28 GMT”,“lati”:46.24,“long”:3.2523,“alti”:145,“rxnb”:2,“rxok”:2,“rxfw”:2,“ackr”:100,“dwnb”:2,“txnb”:2}}

Please see: https://forum.loraserver.io/search?q=gateway%3A%20invalid%20protocol%20version.