FTP suddenly stopped working

We have a nightly process that has been running for 10+ years and suddenly
it stropped working.
The process builds a file called AIRRES on our local ISeries and saves it
to the IFS in /QDLS/MESSAGES,
then FTP's it overseas to our Bangkok server.
The file is being successfully created on our local IFS but FTP fails.

Here is the log:

NAMEFMT 1

500 'SITE NAMEFMT 1': command not understood
Client NAMEFMT is 1.
Enter an FTP subcommand.

LCD /QDLS

Error occurred when resolving a path name.
Enter an FTP subcommand.

LCD MESSAGES

Unknown extension in database file name.
Enter an FTP subcommand.

PUT AIRRES.TXT

Unknown extension in database file name.
Enter an FTP subcommand.

QUIT

221

Pam Gutowski | Senior Programmer Analyst | Grand Circle Corporation,
Boston
Phone (617) 346-6538 | *: pgutowski@xxxxxxxxxxxxx