Hello, I had this error and clearing the cache helped.
Also, make sure you have not changed the slug of any of your taxonomies or preview pages recently, and do a refresh by saving your permalinks.
Changing a taxonomy slug is what triggered the error for me, clearing the cache and saving my permalinks fixed it. I also had to reset the conditions to the new one in cornerstone since changing the slug technically creates a new taxonomy.
Hope this helps someone else.