3CX FTP back-up does not work anymore ever since ProFTPD updated on May 7th 2018

[Dick Goemans]

I have a battery of servers running Ubuntu Linux with Plesk for our hosting environment.
On May 7th Plesk upgraded ProFTP to version 1.3.6 which they compiled on Feb 20th 2018.

proftpd -V
Compile-time Settings:
Version: 1.3.6 (stable)
Platform: LINUX [Linux 4.10.0-35-generic x86_64]
Built: Tue Feb 20 2018 17:32:25 +07

Ever since that date all of the 3CX-servers stopped backing up to that server. I tried different servers with the same outcome (all running ProFTP)

There are several threads with the same header and either they stay unresolved or solved because the OP decided to switch to another FTP-server.
I can't just change the FTP-server.
ProFTP is a major player and I have yet to encounter another FTP-client having problems with it.
It's only 3CX.

None of our clients that have their websites hosted with us have reported any problems since that upgrade.

I put some time and effort in it in 2018 and created a Github issue there: https://github.com/proftpd/proftpd/issues/774

I'm sure that if you change the FTP-client on 3CX to a better one this issue will be resolved.

 

[BrenttG]

Ever since that date all of the 3CX-servers stopped backing up to that server. I tried different servers with the same outcome (all running ProFTP)

I think this sentence spells it out, we use the FTP backup for 100 3CX servers we host in our Datacenter, and it works perfectly fine, we have the FTP offsite for safety but using an IPSEC VPN so the data is encrypted in transit. We havent had any issues with it on 15.5 or 16.0.0.910, and even our Beta server is also backing up perfectly, perhaps check your use of PASV ports, make sure they are proper.

Our server is indeed running ProFTPD

EDIT: Just manually updated ProFTPD and it still works....Not sure why yours wont.... Perhaps enable recording of the transaction in the server an then review the log and find the fault that breaks it. Its usually 100% human readable as all FTP commands are.

EDIT AGAIN: Try this: http://www.proftpd.org/docs/howto/Debugging.html