Hi there, Hoppers!
In the event that this error gets put out, ask yourself two things.
1. How many times am I getting this error?
2. Is the error due to something I changed?
This error generally hints to an API error, in which case the hopper has lost it's link to the API service of the exchange and it produces this error as a result.
Should the error only appear sporadicly it's no issue to worry about, if however, it appears every 20 seconds, please double check your API key and send in a ticket :)