Unfortunately,that’s only one step in a solution. And I don’t recall all the steps.
I had every single error you can think of in the logs.
I’ve cleared caches, re-did permissions, rebuld, etc.
It stops working, I stumble around and it works again.
I also had this error and worked around this to get the campaigns running again. I wouldn’t have known about this had I not gone through the campaign history as it’s not a log error.