I'm experiencing the same issue here @Davidt. Have you been able to resolve this?

this is happening to all of my automations. Any insight?

If anyone runs into this: for me it's because I accidentally went over my automation run limit while building my database and running way too many tests. Word of caution, be more conservative about your tests!! 

Thanks! This was also the problem in my case. The error message is very misleading (I spent a lot of time trying to figure out what was wrong with my conditional group!).

This extremely unhelpful code was cropping up in one of my automations, despite not being over the limits... and it took me a while but I found the solution.

One of my conditions was checking if {Completion} < 1 where {Completion} is a formula field formatted that properly recognizes numerical formatting.  I saw grumblings in another forum post which alluded to the fact that formulas referencing lookup fields can sneakily pass through an array rather than a number which can cause automations to fail.

I thought that the new feature in the lookup field configuration to "Limit the number of items shown to the first 1" would force the lookup to return a single value, but it still appeared to be passing an array with a single number.  So I altered my formula field to explicitly cast the lookup field to a string and then a number. The resulting formula:

{Completion (Lookup)} & "" + 0

This comment just saved me so headache and frustration - THANK YOU!!!!!

Seems like this can be caused by various issues. Check your formulas and fields. Potentially it's related to:

• Lookup fields providing arrays instead of strings/values.
• Changes in field definitions or conditions in lookup fields (check your fields and look out for the red exclamation mark)
• Maybe running over automation limits...check your account for quota.