I just give up(for now anyway). It works on my machine(change the name of the resultFileAbsolutePath.txt to allFilesContent.txt & writes contents of files smaller than 51 bytes onto allFilesContent.txt ). I still can't pass the first validation point: The file passed as the second argument to main must be renamed to allFilesContent.txt. Create a File object with a new file name: allFilesContent.txt. You need to specify the full path. -> I am not sure if that is a problem or it just says it but the problem lays somewhere else?