sensor.total_imported_energy_cost error

[RafAustralia]

hi all

I am getting this error and not sure how to solve this so need some assistance please:

UNTIL TODAY, I HAVE NEVER POSTED ISSUES ON GITHUB SO MIGHT BE DOING IT ALL WRONG
Apologies in advance.

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Logger: homeassistant.helpers.event
Source: helpers/template.py:605
First occurred: June 11, 2024 at 4:51:43 PM (2 occurrences)
Last logged: June 11, 2024 at 4:51:43 PM

Error while processing template: Template<template=({{ (states('sensor.total_imported_energy_cost')) | float |round(2) }}) renders=2>
Error while processing template: Template<template=({{ (states('sensor.total_exported_energy_compensation')) | float |round(2) }}) renders=2>
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 2239, in forgiving_float_filter
return float(value)
^^^^^^^^^^^^
ValueError: could not convert string to float: 'unknown'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 603, in async_render
render_result = _render_with_context(self.template, compiled, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 2616, in _render_with_context
return template.render(**kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/jinja2/environment.py", line 1304, in render
self.environment.handle_exception()
File "/usr/local/lib/python3.12/site-packages/jinja2/environment.py", line 939, in handle_exception
raise rewrite_traceback_stack(source=source)
File "", line 1, in top-level template code
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 2242, in forgiving_float_filter
raise_no_default("float", value)
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 1853, in raise_no_default
raise ValueError(
ValueError: Template error: float got invalid input 'unknown' when rendering template '{{ (states('sensor.total_imported_energy_cost')) | float |round(2) }}' but no default was specified

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 715, in async_render_to_info
render_info._result = self.async_render( # noqa: SLF001
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/homeassistant/homeassistant/helpers/template.py", line 605, in async_render
raise TemplateError(err) from err
homeassistant.exceptions.TemplateError: ValueError: Template error: float got invalid input 'unknown' when rendering template '{{ (states('sensor.total_imported_energy_cost')) | float |round(2) }}' but no default was specified