Custom cards for Lovelace UI in Home Assistant

If this was the first time you created the www folder in your config than you MUST restart Home Assistant.

This is usually caused by running an older frontend. If you're already running 0.73 or newer please make sure you have cleared browser cache. On mobile app you can also force a few refreshes. If you're running IOS device check next question.

You can resolve this issue by upgrading to Home Assistant 0.76 or later. If you are on an older version, make sure you have javascript_version: latest in your configuration.yaml under frontend.

This is most likely because you downloaded the html from gitbut instead of raw. That is not valid javascript. Always make sure you download using raw button. After downloading the file again with the 'raw' button, remember to bump the version number for the custom component speficied in the 'resources' of your lovelace-ui.yaml file.

This is probably because your version of Firefox doesn't have custom components supported or enabled. Please set to true in your about:config the following settings: dom.webcomponents.customelements.enabled and dom.webcomponents.shadowdom.enabled