FileZilla cannot connect to FTP server anymore

[doffine]

Newly we have the problem that we cannot connect to one of our FTP servers anymore. In the FileZilla log we get the following error lines:

Antwort: 425 Unable to build data connection: Operation not permitted
Fehler: Verzeichnisinhalt konnte nicht empfangen werden

After having some mailing with the data center admin we found that adding the line...

TLSOptions NoSessionReuseRequired

...to our FTP server system solved the problem and we were able again to connect to this server.

We tried several other FTP clients (SmartFTP, WinSCP) and none of them had this problem with this FTP server, only FileZilla. Additionally we tested FileZilla client on about five other Windows systems - on every system the same problem occurs.

Now we think it should be possible to connect with FileZilla without having to disable this security feature (TLSOptions NoSessionReuseRequired) in the FTP server system.

Many greetings,
-doffine

[doffine]

We just found the problem: Our data center had updated the server environment to OpenSSL 1.1.1 und ProFTPD 1.3.6c. In this combination it is necessary to set the parameter "TLSOptions NoSessionReuseRequired" for FileZilla to work properly.

Perhaps this information is interesting for FileZilla developers.

[doffine]

Another information on this:

Data center engineers stated, that it is a problem with newer FileZillas and TLS 1.3 with an environment consisting of OpenSSL 1.1.1 und ProFTPD 1.3.6c.

At this moment setting the option "TLSOptions NoSessionReuseRequired" is the only workaround.

So it would be really nice if someone here would attend this problem.

Many greetings,
-doffine