completePendingCommand()

https://commons.apache.org/proper/commons-net/apidocs/org/apache/commons/net/ftp/FTPClient.html#completePendingCommand()

There are a few FTPClient methods that do not complete the entire sequence of FTP commands to complete a transaction. These commands require some action by the programmer after the reception of a positive intermediate command. After the programmer's code completes its actions, it must call this method to receive the completion reply from the server and verify the success of the entire transaction.

but doesn’t seem to help

oddly, i was seeing this stack trace with the sftp tests, adding a connection close action seemed to resolve it

I have a test for this in this PR

I've checked this ticket and confirmed the issue happened on lucee latest version 5.3.8.178-SNAPSHOT also. while using attribute transferMode = binary in cfftp throws an error like Connection is not open. Seems, ACF works fine. change the transferMode to auto or ASCII works fine in lucee too.

"ERROR","ajp-nio-8009-exec-5","05/24/2021","15:45:57","","Connection is not open;Connection is not open;lucee.runtime.exp.NativeException: Connection is not open
at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:474)
at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:608)
at org.apache.commons.net.ftp.FTP.type(FTP.java:1081)
at org.apache.commons.net.ftp.FTPClient.setFileType(FTPClient.java:1519)
at lucee.runtime.net.ftp.FTPClientImpl.setFileType(FTPClientImpl.java:86)
at lucee.runtime.net.ftp.FTPWrap.connect(FTPWrap.java:112)
at lucee.runtime.net.ftp.FTPWrap.<init>(FTPWrap.java:61)
at lucee.runtime.net.ftp.FTPPoolImpl._get(FTPPoolImpl.java:83)
at lucee.runtime.net.ftp.FTPPoolImpl.get(FTPPoolImpl.java:38)
at lucee.runtime.tag.Ftp.getClient(Ftp.java:495)
at lucee.runtime.tag.Ftp.actionPutFile(Ftp.java:397)
at lucee.runtime.tag.Ftp.doEndTag(Ftp.java:185)
at test.testcase.ldev3528.test_cfm$cf$7.call(/test/testcase/LDEV3528/test.cfm:6)
at lucee.runtime.PageContextImpl._doInclude(PageContextImpl.java:945)