Configure date time format of a sensor to display as day and time

I’m trying to configure a sensor created from an attribute of a binary sensor to display the date time in a readable format (day of the week and time in 24h format). I am wanting to change the onset and expires sensors.

Currently I have this as my template:

  - platform: template
                friendly_name: "Meteoalarm - Alert Onset"
                value_template: "{{as_timestamp(state_attr('binary_sensor.meteoalarm', 'Onset')) | timestamp_custom('%A %x %X') }}"
                friendly_name: "Meteoalarm - Alert Certainty"
                value_template: "{{ state_attr('binary_sensor.meteoalarm', 'certainty' ) }}"
                friendly_name: "Meteoalarm - Alert Expires"
                value_template: "{{ state_attr('binary_sensor.meteoalarm', 'expires' ) }}"
                friendly_name: "Meteoalarm - Alert Headline"
                value_template: "{{ state_attr('binary_sensor.meteoalarm', 'headline' ) }}"
                friendly_name: "Meteoalarm - Alert Discription"
                value_template: "{{ state_attr('binary_sensor.meteoalarm', 'Description' ) }}"
                friendly_name: "Meteoalarm - Alert Instruction"
                value_template: "{{ state_attr('binary_sensor.meteoalarm', 'Instruction' ) }}"

and the sensor is showing as unavailable. The sensor before trying to format shows as:

Log error:

TemplateError('ValueError: Template error: as_timestamp got invalid input 'None' when rendering template '{{as_timestamp(state_attr('binary_sensor.meteoalarm', 'Onset')) | timestamp_custom('%A %x %X') }}' but no default was specified') while processing template 'Template<template=({{as_timestamp(state_attr('binary_sensor.meteoalarm', 'Onset')) | timestamp_custom('%A %x %X') }}) renders=4>' for attribute '_attr_native_value' in entity 'sensor.meteoalarm_onset'

As a side point, I’d also like to display the description and instruction attributes as well as currently they only show up as unavailable.

Any ideas?

My guess is that your error is the capitalization of Onset, Description, and Instruction. Try making them all lower case and see if that resolves your issue.

That worked for onset, thank you!

Unfortunately, I get this for description and instruction now:

where they no longer follow the name they were assigned. I found capitalizing resolved that issue initially hence why they were capitalized but clearly onset shouldn’t have been.