OH3.3.0 KNX Binding unstable

ich have a problem regarding OH3.3.0 and KNX Binding. Since the latest upgrade the connection to the knx gateway has become unstable, following output shows in openhab.log frequently.

2022-08-01 07:32:41.366 [INFO ] [ab.event.ThingStatusInfoChangedEvent] - Thing ‘knx:ip:bridge’ changed from ONLINE to OFFLINE (COMMUNICATION_ERROR): server request
[ab.event.ThingStatusInfoChangedEvent] - Thing ‘knx:ip:bridge’ changed from ONLINE to OFFLINE (COMMUNICATION_ERROR): no heartbeat response

THING Config looks like this:

Bridge knx:ip:bridge [
// readingPause=50,
// responseTimeout=10,
// readRetriesLimit=3,
// autoReconnectPeriod=60,
// localSourceAddr=“0.0.0”

Initial Config after before and after the upgrade was without the “//” and worked fine.

Any help highly appreciated!

Hi Andreas,

I have the same problem since yesterday. I had to restart my windows server with the openHAB virtual machine running on centOS.
But the update only affected the server. an older version of openHAB 3.1 (Friday) also no longer gets a KNX connection.
Sometimes I get the message “could not accept new connection (maximum reached)”.
All my searches and attempts were unsuccessful.

I use the GIRA IP Interface (not router)


Hi Kai,

“maximum reached” is a different problem. Usually the KNX Gateways have maximum number of sessions, so when they´re all block by openhab, ETS etc. or may not be properly closed, the sessions are stuck on the knx ip gw. In that case on my side helps to “shut / no shut” the switchport where the knx ip gw is connected.


I know that’s a different problem, but I much more often have your messages and:
“The KNX network link was detached from the process communicator” and
“KNX link has been lost (reason: server request on object tunneling link (closed) TP1 medium, device 0.0.0, hopcount 6)” and
“Establishing connection to KNX bus on in mode TUNNEL.”

Do you mean closing and opening the switch port is different than pulling the LAN plug and de-energizing the gateway.
Do you speak german? :wink:

Liebe Grüße

Log from today:

2022-08-09 11:52:03.190 [WARN ] [net/IP Tunneling] - **received disconnect response status 0x21 (no active data connection with that ID**)
2022-08-09 11:52:03.199 [ERROR] [net/IP Tunneling] - **close connection - maximum send attempts**
tuwien.auto.calimero.KNXAckTimeoutException: maximum send attempts, no service acknowledgment received
        at tuwien.auto.calimero.knxnetip.ConnectionBase.send(ConnectionBase.java:253) ~[?:?]
        at tuwien.auto.calimero.knxnetip.KNXnetIPTunnel.send(KNXnetIPTunnel.java:213) ~[?:?]
        at tuwien.auto.calimero.link.KNXNetworkLinkIP.onSend(KNXNetworkLinkIP.java:423) ~[?:?]
        at tuwien.auto.calimero.link.AbstractLink.send(AbstractLink.java:385) ~[?:?]
        at tuwien.auto.calimero.link.KNXNetworkLinkIP.sendRequestWait(KNXNetworkLinkIP.java:402) ~[?:?]
        at tuwien.auto.calimero.mgmt.TransportLayerImpl.sendData(TransportLayerImpl.java:351) ~[?:?]
        at tuwien.auto.calimero.mgmt.ManagementClientImpl.send(ManagementClientImpl.java:1275) ~[?:?]
        at tuwien.auto.calimero.mgmt.ManagementClientImpl.send(ManagementClientImpl.java:1259) ~[?:?]
        at tuwien.auto.calimero.mgmt.ManagementClientImpl.sendWait2(ManagementClientImpl.java:1295) ~[?:?]
        at tuwien.auto.calimero.mgmt.ManagementClientImpl.readDeviceDesc(ManagementClientImpl.java:595) ~[?:?]
        at tuwien.auto.calimero.mgmt.ManagementProceduresImpl.isAddressOccupied(ManagementProceduresImpl.java:391) ~[?:?]
        at org.openhab.binding.knx.internal.client.AbstractKNXClient.isReachable(AbstractKNXClient.java:355) ~[?:?]
        at org.openhab.binding.knx.internal.handler.AbstractKNXThingHandler.pollDeviceStatus(AbstractKNXThingHandler.java:147) ~[?:?]
        at org.openhab.binding.knx.internal.handler.AbstractKNXThingHandler.lambda$1(AbstractKNXThingHandler.java:187) ~[?:?]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
        at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) [?:?]
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) [?:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
        at java.lang.Thread.run(Thread.java:829) [?:?]

After: openhab> bundle:restart org.openhab.binding.knx
It works again …