FTP Connector not working after update to 4.3.2

Hello @tobias.koetter and @ScottF

I updated my Knime version to 4.3.2 and my FTP workflow did not work on this version.
Error message:
WARN FTP Connector 0:745 Failed to create 1-th FTP session (0 sessions already opened). Please consider decreasing the maximum FTP sessions.
ERROR FTP Connector 0:745 Failed to initialize FTP client pool
ERROR FTP Connector 0:745 Execute failed: Failed to connect with FTPS

So I reinstalled this last version and installed 4.3.1 and it works as it should…

Hi @Anna_H and welcome to the forum.

Were you trying to connect to a public FTP site when you got this error? If so can you share the URL so we can try to reproduce?

Do you happen to have the stack trace from the KNIME logs as well? And what operating system are you using?


Hi @Anna_H -

Just checking in to see if you’re still having problems here?

Hello @ScottF thank you for your message and sorry for the late reply. The FTP is a private one. Actually I have two versions of KNIME 4.3.1 and 4.3.2 on the same laptop.

Regarding 4.3.1., there is no problem and the WF runs right.
But 4.3.2, the same WF does not work. Here is an extraction of log

   Caused by: javax.net.ssl.SSLHandshakeException: Hostname doesn't match certificate
	at org.apache.commons.net.ftp.FTPSClient.sslNegotiation(FTPSClient.java:295)
	at org.apache.commons.net.ftp.FTPSClient._connectAction_(FTPSClient.java:225)
	at org.apache.commons.net.SocketClient._connect(SocketClient.java:244)
	at org.apache.commons.net.SocketClient.connect(SocketClient.java:202)
	at org.knime.ext.ftp.filehandling.fs.FtpClientFactory.createNativeClient(FtpClientFactory.java:129)

Perhaps there is a problem with certificates here…? Is it possible that you have installed the appropriate certificates in your 4.3.1 version, but not the more recent version?

To install the necessary certificates in your KNIME AP cacerts file, you can follow the client configuration section in our documentation.

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