While evaluating the template, the sensor's value was unavailable
states.sensor.tvattmaskin_energi.state | float
The float filter cannot convert unavailable to a number.
When this happened in previous versions of Home Assistant, float would simply convert unavailable to 0 and say nothing. However, now it tells you that this incident occurred and warns you that you should provide float with a default value (you decide what that value should be).
If you want float to use 0 as a default value, just specify it like this everywhere you use it in your templates:
float(0)
For example:
value_template: >
{% if states.sensor.tvattmaskin_energi.state | float(0) > 3.0 %}
{{ "Running" }}
{% elif states.sensor.tvattmaskin_energi.state | float(0) > 1 %}
{{ "On" }}
{% else %}
{{ "Off" }}
{% endif %}
For more information, refer to: