Please set the loglevel to TRACE and PM me the log. I‘ll reproduce the issue and fix it asap.
I have the same error with my Vitocal 250 A. Hope for a quick solution.
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Same here 
@maihacke @pumpi @Radioaktivman
I’m almost done with the fix. I still need to complete the automatic migration. I hope to have it finished by Sunday.
4 Likes
It seems that DHWonetimecharge does not work any more. Can anybody confirm this?
05:48:11.440[INFO] [openhab.event.ItemCommandEvent] - Item 'Viessmann_DHWonetimechargefunctionactive' received command ON
05:48:11.441[INFO] [openhab.event.ItemStatePredictedEvent] - Item 'Viessmann_DHWonetimechargefunctionactive' predicted to become ON
05:48:11.443[INFO] [openhab.event.ItemStateUpdatedEvent] - Item 'Viessmann_DHWonetimechargefunctionactive' updated to ON
05:48:11.443[INFO] [openhab.event.ItemStateChangedEvent] - Item 'Viessmann_DHWonetimechargefunctionactive' changed from OFF to ON
05:48:13.745[INFO] [openhab.event.ItemStateUpdatedEvent] - Item 'Viessmann_OperatingmodeactiveCircuit1' updated to dhwAndHeating
05:48:13.748[INFO] [openhab.event.ItemStateUpdatedEvent] - Item 'Viessmann_OperatingprogramactiveCircuit1' updated to reduced
05:48:13.753[INFO] [openhab.event.ItemStateUpdatedEvent] - Item 'Viessmann_DHWonetimechargefunctionactive' updated to OFF
05:48:13.753[INFO] [openhab.event.ItemStateChangedEvent] - Item 'Viessmann_DHWonetimechargefunctionactive' changed from ON to OFF
05:48:13.753[INFO] [openhab.event.ItemStateUpdatedEvent] - Item 'Viessmann_DHWonetimechargefunctionstatus' updated to OFF
05:48:13.757[INFO] [openhab.event.ItemStateUpdatedEvent] - Item 'Viessmann_DHWtemperaturesensor' updated to 31.2 °C
I can’t confirm this. It works on my installation. Please send me the full log in `TRACE` mode via PM
FYI: I just discovered the following in my logs:
==> /logs/openhab.log <==
2025-09-27 12:22:30.785 [INFO ] [.viessmann.internal.api.ViessmannApi] - API IOException: Unable to execute GET: java.util.concurrent.ExecutionException: org.eclipse.jetty.client.HttpResponseException: HTTP protocol violation: Authentication challenge without WWW-Authenticate header
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Hello everyone, I would like to inform you that a new version has now been released.
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Hi @rogrun ,
i see the update in the binding information shown in the openhab UI. However, i am not sure if openhab updated it automaticly. The openhab console shows the following:
346 │ Active │ 80 │ 5.1.0.202509101920 │ openHAB Add-ons :: Bundles :: Viessmann Binding
Can you confirm, that it is the most recent version you provided?
Using the above version, I now observe that the Gasboiler thing and the Bridge thing do not go online, when enabling both.
The log files show the follwoing entries:
2025-09-29 11:52:05.460 [INFO ] [.viessmann.internal.api.ViessmannApi] - API IOException: Unable to execute GET: java.util.concurrent.ExecutionException: org.eclipse.jetty.client.HttpResponseException: HTTP protocol violation: Authentication challenge without WWW-Authenticate header
2025-09-29 11:52:05.476 [INFO ] [.viessmann.internal.api.ViessmannApi] - API IOException: Unable to execute GET: java.util.concurrent.ExecutionException: org.eclipse.jetty.client.HttpResponseException: HTTP protocol violation: Authentication challenge without WWW-Authenticate header
This is an old version. Please remove the binding and reinstall it from the marketplace.
Don’t remove things. They will update automatically.
If this problem persists in the new version, I need more log in TRACE mode via PM
I Installed the update and the binding is now running. thx @rogrun for your work
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I updated as well: Gasboiler is running.Thank you!
FYI: I now see the following warning
2025-10-03 09:22:06.725 [WARN ] [smann.internal.handler.DeviceHandler] - Unknown unit. Could not parse unit: kilowatt of Feature: heating.compressors.0.power - Please open an issue on GitHub.
@Radioaktivman thanks for your report. I‘ll take a look.
I also get a warning:
2025-10-14 18:51:03.661 [WARN ] [smann.internal.handler.DeviceHandler] - Unknown unit. Could not parse unit: revolutionsPerSecond of Feature: heating.compressors.0.speed.current - Please open an issue on GitHub.
Please send me your log in trace mode via PM. I need to verify the API response from your device.
Okay, log in trace mode is sent.
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I published a new version with the fix. Please remove the binding and re-install it from the marketplace.
Great, with the new version of the binding, the error for “Unknown unit revolutionsPerSecond” is gone. Thanks a lot!
1 Like
After latest update of openhab and openhab-addons (version 5.0.2) I got those Warnings for all of my (viessmann-) items defined in an *.items file:
2025-10-20 17:48:10.644 [WARN ] [ore.common.registry.AbstractRegistry] - Cannot add “ItemChannelLink” with key “HEAT1_SolarDhwTemp → viessmann:device:e430492222:7637415008955257:0:heating-solar-sensors-temperature-dhw”. It exists already from provider “GenericItemChannelLinkProvider”! Failed to add a second with the same UID from provider “ManagedItemChannelLinkProvider”!
2025-10-20 17:48:10.645 [WARN ] [ore.common.registry.AbstractRegistry] - Cannot add “ItemChannelLink” with key “HEAT1_GasConsumptionDay → viessmann:device:e430492222:7637415008955257:0:heating-gas-consumption-total#today”. It exists already from provider “GenericItemChannelLinkProvider”! Failed to add a second with the same UID from provider “ManagedItemChannelLinkProvider”!
2025-10-20 17:48:10.646 [WARN ] [ore.common.registry.AbstractRegistry] - Cannot add “ItemChannelLink” with key “HEAT1_DhwOneTimeChargeStatus → viessmann:device:e430492222:7637415008955257:0:heating-dhw-one-time-charge#status”. It exists already from provider “GenericItemChannelLinkProvider”! Failed to add a second with the same UID from provider “ManagedItemChannelLinkProvider”!
<and so on...>
I have to say, the binding was not installed after the update anymore.
I do not know, why the openhab update removed the viessmann binding by itself.
So the account, gateway and drive thing got an HANDLER_INITIALIZING_ERROR first.
Then I installed the binding again and then got the mentioned warnings after starting the account thing once.
How to get rid of these warnings?
(By the way, a simple reboot does not help. The warnings occured again.)
Hi @rogrun
Many thanks for this Binding and after your update Sept. 29 it works for me.
But for the following channels I get no values:
heating-burners-0-statistics#hours,
heating-circuits-0-heating-curve#shift and
heating-circuits-0-heating-curve#slope
openHAB 5.0.1 on Raspi 4
Gasboiler Vitodens 300-W