Fronius binding producing error in OH 3.1.0 M5

I did an upgrade to 3.1.0 M5 and tried to use Fronius the binding accessible from the user interface, added bridge, smartmeter, inverter, connected smartmieter and inverter to the bridge by user interface. The bridge seems to open fine, smartmeter and produce ERROR:COMM:

2021-06-01 13:47:46.885 [INFO ] [ab.event.ThingStatusInfoChangedEvent] - Thing 'fronius:powerinverter:FroniusBR:FroniusSI' changed from OFFLINE (COMMUNICATION_ERROR): Invalid JSON data received to OFFLINE (COMMUNICATION_ERROR): java.util.concurrent.ExecutionException: java.io.EOFException: HttpConnectionOverHTTP@4610d9::SocketChannelEndPoint@d70725{l=/192.168.178.8:41500,r=/192.168.178.78:80,ISHUT,fill=-,flush=W,to=4/0}{io=0/0,kio=0,kro=1}->HttpConnectionOverHTTP@4610d9(l:/192.168.178.8:41500 <-> r:/192.168.178.78:80,closed=false)=>HttpChannelOverHTTP@a66a38(exchange=HttpExchange@1d856c9{req=HttpRequest[GET /solar_api/v1/GetPowerFlowRealtimeData.fcgi HTTP/1.1]@1905933[TERMINATED/null] res=HttpResponse[null 0 null]@1489ecb[PENDING/null]})[send=HttpSenderOverHTTP@42c370(req=QUEUED,snd=COMPLETED,failure=null)[HttpGenerator@151ac2f{s=START}],recv=HttpReceiverOverHTTP@bd24f7(rsp=IDLE,failure=null)[HttpParser{s=CLOSED,0 of -1}]]

bundle shows:

238 │ Active │ 80 │ 3.1.0.M5 │ openHAB Add-ons :: Bundles :: Fronius Binding

openhab / openhab-addons

Fronius binding producing error in OH 3.1.0 M5 #10789