Error parsing value: 'value_json' is undefined... / MQTT

I have a problem with an ethernet controlled relay over MQTT and I have no idea what might be wrong (it has worked)
Are these errors related (the cause of or a result) to the problem because I don’t understand what it means.

This is from the logfile:

Logger: homeassistant.helpers.template
Source: helpers/template.py:592
First occurred: 11:41:15 (19 occurrences)
Last logged: 11:41:15

Error parsing value: 'value_json' is undefined (value: MQTT Publish Setting, template: {{ value_json.relay7.on }})
Error parsing value: 'value_json' is undefined (value: MQTT Publish Setting, template: {{ value_json.relay8.on }})
Error parsing value: 'value_json' is undefined (value: MQTT Publish Setting, template: {{ value_json.relay9.on }})
Error parsing value: 'value_json' is undefined (value: MQTT Publish Setting, template: {{ value_json.relay10.on }})
Error parsing value: 'value_json' is undefined (value: MQTT Publish Setting, template: {{ value_json.relay11.on }})

Logger: homeassistant.helpers.template
Source: helpers/template.py:589
First occurred: 11:41:15 (19 occurrences)
Last logged: 11:41:15

Template variable error: 'value_json' is undefined when rendering '{{ value_json.relay7.on }}'
Template variable error: 'value_json' is undefined when rendering '{{ value_json.relay8.on }}'
Template variable error: 'value_json' is undefined when rendering '{{ value_json.relay9.on }}'
Template variable error: 'value_json' is undefined when rendering '{{ value_json.relay10.on }}'
Template variable error: 'value_json' is undefined when rendering '{{ value_json.relay11.on }}'

Definition of switches in mqtt.yaml:

- name: 'relay16B-1'
  unique_id: relay16B-1
  state_topic: 'relay16/2154d5e0aa46831378722ee8/state'
  command_topic: 'relay16/2154d5e0aa46831378722ee8/set'
  payload_on: '{"relay1":{"on":1}}'
  payload_off: '{"relay1":{"on":0}}'
  value_template: '{{ value_json.relay1.on }}'
  state_on: 1
  state_off: 0

Thanks in advance for any help!