This appears to be a case where the file_id values in the CubeCart_filemanager table got renumbered somehow.
I think your best approach to this is to download the backup that CubeCart made on the upgrade attempt, extract the SQL dump for the CubeCart_filemanager table, and see if there is a record with file_id of 15725 there. (It's all plain text, so a competent text editor should be able to search for 15725.)
If that record is there, then I suggest you replace the existing table contents with the SQL structure and contents for that table you just extracted.