_FTPERROR returns the error code of the last error reported by FTP. Some of the possible codes are:

 

101You cannot change the remote host at this time        
102The remote host address is invalid        
118Firewall error        
141FTP protocol error        
142Communication error        
143Busy performing current action        
144Local file error        
145Can't open local file for reading        
146No remote file specified while uploading        
147Data interface error        
301Operation interrupted        
302Can't open local file        
311Accept failed for data connection        
312Asynchronous select failed for data connection        
11001Host not found        
11002Non-authoritative 'Host not found'        
11003Non-recoverable errors: FORMERR, REFUSED, NOTIMP        
11104Valid name, no data record (check DNS setup)