the directory /data/ exists ( or expect that it is created? )
the file exists already at /data/filename
( or that it is created by that code? )
– but your code does not create anything here
( win7 64bit / processing 3.5.3. )
otherwise,
if i create the path and file manually,
the used file exists and delete functions work just fine.
next time you paste code please
just play/post for one fix test filename
( and not with 3 created filenames )
and make it a short but RUNnable code
here the full way, with directory and file creation
what is somehow useless as processing can not use existing empty files for append?
more a academic exercise