Weird file corruption when using FTP. Any theories?

Solution 1:

Very simply: the universe (and/or Murphy) is punishing you for continuing to use a thoroughly obsolete and insecure protocol like FTP.

When you connect to your web server using FTP, your username and password are sent unencrypted, in the clear, for everyone and Big Brother to read. So are the contents of all the files that you upload or download using FTP. For security reasons alone, I would strongly suggest switching to SFTP, which is a built-in feature of SSH. Any web hosting provider worth your business supports SSH and SFTP.

Any FTP problems that you may be experiencing on the server side almost certainly will not apply when using SFTP, because SFTP connections are handled by a completely separate daemon/service on the server.

Unlike FTPS, FTPES, etc., SSH/SFTP implementations are very consistently interoperable. You are unlikely to experience strange and unpredictable problems when transferring files via SFTP.

Solution 2:

My money is on a FTP server bug (your host's problem). Make sure you are using the latest version of FileZilla, and configure it to log all your FTP sessions so that if you discover this corruption, you can provide the host with a log of the session. It might help them troubleshoot.

If you have shell access to your host, you could use SCP instead.

Solution 3:

just to be on safe side, I'd make sure transfer set to "binary" sometimes it transfer files in ASCII mode and that's where you usually get so to speak corruption, so try that if that doesn't solve your problem then I'd look into replacing/updating your server & client and if that doesn't help either then look on interface if you're getting errors there...

Solution 4:

for me this was because of the transfer mode set to ASCII in filezilla, i set Transfer -> Transfer type -> Auto, (to ensure it uses binary mode when required)

this solved my issue. Hope this helps you guys as well.