Debugging error message

Hi there,

I’ve been getting the following error for a while :

Logger: homeassistant.config
First occurred: 16:34:55 (1 occurrences)
Last logged: 16:34:55

Invalid config for [automation]: invalid template (TemplateSyntaxError: expected token ‘,’, got ‘sensor’) for dictionary value @ data[‘action’][0][‘data’]. Got None. (See ?, line ?).

How do I find out which automation is causing this error?
The error message came after an update (I’m not sure which one)

HA 2018.8 Hacs1.13.2
Please advise.