GZP Files can be corrupted when transferred with FTP command. (This can affect any file type.) The problem can be resolved on the client or server. The client can be changed into "binary mode" or the server can be set to "ignore ASCII mode". NEVER USE "ASCII" MODE.

The problem is that the file is being translated by the server when transferred in "ASCII" type/mode. ASCII type transfer mode converts "newline" (EOL) codes in a file to match the platform of the target. (Doc explaining ASCII vs Binary) This was really handy a very long time ago, but now it just corrupts files. Unfortunately, the FTP command line client defaults to "ASCII" mode, so you have to switch modes with the "binary" command every time after connecting to a server. IMPORTANT: YOU HAVE TO DO THIS EVERY TIME!

FTP Server fix: FileZilla is a free Windows FTP server that does NOT corrupt files when transferred in ASCII type mode. (and there are plenty of others for every platform)

There are 3 ways to FTP a file from the system controller:

1. FTP command
2. FTP-PM (graphical)
3. FireFTP (Firefox Addon).

FireFTP Firefox addon is the best and defaults to Auto and will use binary for .gzp files. The command line is preferred for simple transfers (but remember to switch to binary mode). Most FTP servers can ignore ASCII mode, this is also the best way to prevent corruptions.

FireFTP Firefox addon. See Install FTP Client on System Controller (or Virtual Workstation)... for installation and use. Defaults to binary mode.

FTP command client:

Start a OS/2 command window, navigate to the folder containing the file to transfer ("cd d:") and then type "ftp <hostname>", then "binary" to switch transfer mode, then "put <filename>".

From a FTP command prompt, check the transfer mode with the STATUS command, it should say something similar to:
Connected to <servername>.
No proxy connection.
Mode: stream; Type: binary; Form: non-print; Structure: file
Verbose: on; Bell: off; Prompting: on; Globbing: on
Store unique: off; Receive unique: off
Case: off; CR stripping: on
Ntrans: off
Nmap: off
Hash mark printing: off; Use of PORT cmds: on

FTP-PM - A graphical FTP client launched from eCS > Desktop > Internet > Internet Utilities > FTP-PM. It's a little slow.

Choose Options > Transfer Mode > Binary. (Transfer Mode appears in lower right hand corner)