Answered Code: 200 OK {"success":false,"message":"Processor not found: getlist","total":0,"data":[],"object":[]}

Old thread I know, but I just ran in to this after inheriting a 2.2.12 site and upgrading to 2.6.5. hedonle's solution still works. It's line 26 in /assets/components/articles/js/article/update.js - replace the entire line with:

process: 'resource/update'

and it works. I hate updating a file like that but it's the only way I found to get it working right.