Z-Wave JS UI Driver: Failed to open the serial port Cannot lock port (ZW0100)

Maybe the glossary will help:

  1. https://www.home-assistant.io/docs/glossary/#integration
  2. https://www.home-assistant.io/docs/glossary/#add-on

In this case, the add-ons are communicating with the Z-Wave controller and hosting a server, and the Z-Wave integration talks to a server running in the add-on, instead of directly to the controller.

I’ve uninstalled the Z-Wave JS add-on. Not sure how or where to uninstall the integration.

Did you not install the integration in the first place to get to this point? Integrations are added/removed/configured in Settings → Devices & Services. Presumably, you installed the integration and said that you wanted to use the Supervisor add-on, and if you did that, HA will not stopping re-installing it, even if you uninstall it. To break this cycle requires either uninstalling the integration, or re-configuring it.

Those are both the wrong URLs for the ZUI add-on. Be sure to read the accompanying documentation when you install an add-on, which is visible from the add-on page itself, and for ZUI also here: https://github.com/hassio-addons/addon-zwave-js-ui/blob/cbe714b48d81d09702bfbb79317264460bb5e38b/zwave-js-ui/DOCS.md#setting-up-the-home-assistant-z-wave-js-integration

In the next dialog it will ask for the server. Enter: ws://a0d7b954-zwavejs2mqtt:3000

FYI, this configuration is also mentioned in the integration docs: https://www.home-assistant.io/integrations/zwave_js/#installing-and-configuring-the-z-wave-integration-in-home-assistant (emphasis mine)

If you’re running full Home Assistant with supervisor, you will be presented with a dialog that asks if you want to use the Z-Wave JS Supervisor add-on. You must uncheck this box if you are running the Z-Wave JS server in any manner other than the official Z-Wave JS add-on, including using Z-Wave JS UI add-on.

If you’re not running the supervisor or you’ve unchecked the above-mentioned box, you will be asked to enter a websocket URL (defaults to ws://localhost:3000). It is very important that you fill in the correct (Docker) IP/hostname here. For example for the Z-Wave JS UI add-on this is ws://a0d7b954-zwavejs2mqtt:3000.

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