I'm trying to use the utl_file.fopen command (in this case to write a new file out, using SQL Developer v4.1.5.21.78 with Oracle and PL/SQL v12.2.0.1.0, and I just can't seem to shake the ORA-29823 - "invalid file operation" error.

It seems pretty clear it is a permissions issue, but I simply can't track it down. I've made sure to do the following:
> Establish the required directory in All_Directories table.
> Ensured the Oracle user has Write permissions on that folder in All_tab_Privs (It seems to default to include Read/Write/Execute).
> Ensure that I've used the specified directory name in the utl_file.fopen command.
> Ensured the folder exists in the server OS
> Ensured that the Oracle user account (in Windows) has full privileges on the subject folder. (When logged in as that user, I can create/edit/delete files at will.)

If I understand correctly, I shouldn't expect to need to modify init.ora with the versions I have, but maybe that's the missing piece? If adjustments are not necessary in init.ora, then I just don't know where else to look to make this command work.

Excerpts from the code are as follows:

I manually ran this to create the directory entry:

CREATE OR REPLACE DIRECTORY POLY_FILES AS 'C:\Approved_Locations\polygons';

Then, in the code attempting to write out there exists:

DECLARE
  filPoly utl_file.file_type;

  filPoly := utl_file.fopen('POLY_FILES', strFileName, 'w');

Where strFileName is just the name of the file, which I know is valid because I output this value to the Dbms Output right before this line.

thanks for any advice/insight.
e

DECLARE
  filPoly utl_file.file_type;
BEGIN
  filPoly := utl_file.fopen('MY_DEMO_DIR', 'test.dat', 'w');