Z/OS Connector: error message ERROR: failed to list available jobs

[Martin Herbst]

I have got two Jenkins installation and from both installations I am executing jobs on an IBM z/OS.  (with the same user id). On the first machine everything works fine, but on the second machine I have got several problems (tested with pipeline and free style job):

1. If I set the wait time to indefinite, the Jenkins Job never returns
2. With a wait time of 1 minute I get the following messages after about 2.5 minutes (the job was finished on the z/OS after some seconds).

14:36:28 FTP: connected to 10.0.0.35:21
14:36:28 Submitted job [JOB08080]
14:36:39 FTP: connected to 10.0.0.35:21
14:39:17 ERROR: failed to list available jobs
14:39:17 FTP: connected to 10.0.0.35:21
14:39:19 FTP: connected to 10.0.0.35:21
14:39:19 Found job JOB08080 with name MH1 in JES
14:39:19 Will check JOB status in 'MH       OUTPUT A        RC=0000 11 spool files '
14:39:19 FTP: connected to 10.0.0.35:21
14:39:19 Job [JOB08080] processing finished. Captured RC = [0000]

The connector plugin is able to retrieve the job output and also removes the job from the spooler. What could be the reason for this problem? The strange thing is that it is working fine (since months) in the one Jenkins installation but causes this problem in the newer installation.

Plugin version is 2.3.2 on both installations, the Jenkins versions are both 2.204.3 on the machine were it works and 2.204.5 on the machine where it has this problem.

JESINTERFACELEVEL=2 ist set on the z/OS.

[Martin Herbst]

I think, I have found the reason for the problem: it seems that the firewall blocked it somehow.