Hello, I am rather new in all of this technology.
I got a new Homematic CCU3 and try now to connect it with the Homematic Binding 2.3. It tries to initialize the gateway and ends with the following error:
Status: OFFLINE - COMMUNICATION_ERROR Unknown XML-RPC tag: title
Firmware: 3.41.11
I set the firewall settings on the ccu3 already to allow anything. Any suggestions?
Hi Don, you need to upgrade your OH to something like 2.4M6
Ah ok, but 2.4m isnĀ“t stable correct? So I need to change the repo and run apt get install openhab2 again. Does it just update and keep my settings or is it going to reset my whole setup?
It is 95% stable 
that extra 5% of instability will come if you deploy some buggy addon.
The core and 95% of use cases are very stable (imho)
No problems have been reported since itās launch: [OH 2.4.0 M6] Testing Results
That is good to know. Do you know something about the update process from stable to snapshot? I have OH installed on Ubuntu so I have to update it manualy by apt.
Will my setup survive the update? 
I have already AVM FritzBox and Osram Lightify binding with several things running and additional HomeKit integration.
to milestone or snapshot?
if you are using apt: follow the installation instructions on openHAB on Linux | openHAB
Change to the appropriate repo (testing=milestones or unstable=snapshots) and simply apt update and apt install (it will deploy 2.4.0 M6 on top of your existing 2.3.0 Stable and effectively upgrade it). I have added some info in the FAQ around this.
From 2.3.0 Stable to 2.4.0 M6: absolutely yes. I donāt remember any major breaking change (outside Z-Wave) that should give you lots of troubles. Backup your OH2.3.0 first of course.
Great thank. I will go ahead and try the update later tonight. 
openhab-cli backup [file] first
better safe than sorry
if you get stuck, we are here 
OK, update was successfull. So far so good.
Even the CCU was discoverd automatically and appears in the inbox. But while adding it it stucks on āInitializingā
Manaully adding gives the same resultā¦
anything in the openhab.log?
2018-11-22 21:11:58.297 [WARN ] [core.thing.internal.ThingManagerImpl] - Disposing handler for thing āhomematic:bridge:e4b325c7ā takes more than 5000ms.
2018-11-22 21:13:19.869 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing āosramlightify:power:84-18-26-00-00-0E-F4-D5ā to inbox.
2018-11-22 21:25:47.617 [WARN ] [core.thing.internal.ThingManagerImpl] - Disposing handler for thing āhomematic:bridge:3014F711A0001F98A99A42ADā takes m$
2018-11-22 21:25:55.786 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing āhomematic:bridge:3014F711A0001F98A99A42ADā to inbox.
maybe sothing more interesting ā¦
2018-11-22 20:26:33.781 [ERROR] [ome.core.thing.internal.ThingManager] - Exception occurred while disposing handler of thing āhomematic:bridge:a4996c41ā$
java.lang.NullPointerException: null
at org.openhab.binding.homematic.internal.discovery.HomematicDeviceDiscoveryService.waitForScanFinishing(HomematicDeviceDiscoveryService.java:17$
at org.openhab.binding.homematic.internal.discovery.HomematicDeviceDiscoveryService.stopScan(HomematicDeviceDiscoveryService.java:121) [222:org.$
at org.openhab.binding.homematic.handler.HomematicBridgeHandler.dispose(HomematicBridgeHandler.java:143) [222:org.openhab.binding.homematic:2.3.$
at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
at org.eclipse.smarthome.core.internal.common.AbstractInvocationHandler.invokeDirect(AbstractInvocationHandler.java:153) [101:org.eclipse.smarth$
at org.eclipse.smarthome.core.internal.common.Invocation.call(Invocation.java:53) [101:org.eclipse.smarthome.core:0.10.0.oh230]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
at java.lang.Thread.run(Thread.java:748) [?:?]
This is the problem but I donāt know what is the root-causeā¦ searching github now
can you try to: Clear tmp&cache, remove all Homematic Things and re-install the binding?
Removing all HM things, basically only ccu 
uninstalled binding
reboot
installed binding
added HM
still only initializing.
but how I can clean the cache? or did the reboot already cleaned the cache?
still the same 
You may try to open up a github issue for this NPEā¦ I donāt know what could be the root-causeā¦
I think my installation is brickedā¦
Just noticed that my fritz box binding is now also not workingā¦ even fritz box and all things were online.
Have removed the fritzbox and now while adding it back, it stucked at initializingā¦ :-(
I am going to setup a new vm and try with a new fresh setup once againā¦ then directly with 2.4
brand new setupā¦ all new binsing are not workling.
same issue like before on old system with homematic. now with avm. so testing builds are really not stable :-/
2018-11-23 21:37:17.857 [WARN ] [ig.xml.osgi.XmlDocumentBundleTracker] - The XML document ā/ESH-INF/binding/binding.xmlā in module āorg.openhab.binding.avmfritzā c$
java.lang.IllegalArgumentException: The XmlConfigDescriptionProvider must not be null!
at org.eclipse.smarthome.core.binding.xml.internal.BindingInfoXmlProvider.(BindingInfoXmlProvider.java:59) ~[?:?]
at org.eclipse.smarthome.core.binding.xml.internal.XmlBindingInfoProvider.createDocumentProvider(XmlBindingInfoProvider.java:141) ~[?:?]
at org.eclipse.smarthome.config.xml.osgi.XmlDocumentBundleTracker.acquireXmlDocumentProvider(XmlDocumentBundleTracker.java:180) ~[100:org.eclipse.smarthome$
at org.eclipse.smarthome.config.xml.osgi.XmlDocumentBundleTracker.addingObject(XmlDocumentBundleTracker.java:205) ~[100:org.eclipse.smarthome.config.xml:0.$
at org.eclipse.smarthome.config.xml.osgi.XmlDocumentBundleTracker.parseDocuments(XmlDocumentBundleTracker.java:351) [100:org.eclipse.smarthome.config.xml:0$
at org.eclipse.smarthome.config.xml.osgi.XmlDocumentBundleTracker.processBundle(XmlDocumentBundleTracker.java:337) [100:org.eclipse.smarthome.config.xml:0.$
at org.eclipse.smarthome.config.xml.osgi.XmlDocumentBundleTracker.access$4(XmlDocumentBundleTracker.java:332) [100:org.eclipse.smarthome.config.xml:0.10.0.$
at org.eclipse.smarthome.config.xml.osgi.XmlDocumentBundleTracker$2.run(XmlDocumentBundleTracker.java:307) [100:org.eclipse.smarthome.config.xml:0.10.0.oh2$
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:264) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
at java.lang.Thread.run(Thread.java:834) [?:?]
all bindings throw the same warn?
The XML document ā/ESH-INF/binding/binding.xmlā in module [...] c$ java.lang.IllegalArgumentException: The XmlConfigDescriptionProvider must not be null! ?
I just tried M6 and installed avm & homematic and it doesnāt give me any warningsā¦
I have seen this error usually associated with an old JVM (or openJDK)
what is your java -version ?
java version ā11.0.1ā 2018-10-16 LTS
Javaā¢ SE Runtime Environment 18.9 (build 11.0.1+13-LTS)
Java HotSpotā¢ 64-Bit Server VM 18.9 (build 11.0.1+13-LTS, mixed mode)
oracle latest build