You're using docker as a "folder". Nothing wrong with that per se, but it's within the "system" share which is currently setup to move files from the cache pool to the array.
Docker Folder does not like being moved around, as only part of the files will ever get moved around. Either change it to be an image or switch the system share to a cache only share (primary storage of cache and no secondary storage)
Either way, you're going to have to go into Settings, Docker disable the service, switch to advanced view and then delete the image. Then re-enable the service and head over to Apps, Previous Apps and check off what you want installed and from the bottom of the screen Install X Applications.