Edifact renames files to signify that they have been processed.. this is part of the specification. However, if somehow there's already a file with the name you are attempting to change to, currently the process just aborts. We should really record the error somewhere and move on to the next file otherwise we stop processing files until the erroneous file is cleaned up on the vendors site. This is rare though.. so perhaps a low priority.. leaving it here just in case someone else hits this and it gives some good clues ;)