Hello, you have done the fisrt good steps for troubleshooting this issue. It seems that only the perl script cannot interact properly with this FTP server and this OS, the remote one. Please let us know the versions of the OS, FTPD and post some perl code, if possible. Looks like a compatibility issue, since the script is working against other OSes and some other FTP servers. It is important to answer the following questions as well - Have I changed the script, what OSes and FTP servers my script works with, and what's the difference on the remote end, in this particular task. Can you execute the same task against other machine ? Are there any special characters or Windows-like paths in the script ? I have seen "bad file descriptor" with either corrupted test source file, or against Windows FTP - I was missing the correct Windows path represenation. HTH.