gsktrace can be your friend. See https://www.ibm.com/docs/en/cics-ts/6.x?topic=trace-capturing-zos-system-ssl
There will be a LOT of detail but it will tell you exactly what failed. Assuming whatever you're doing lends itself to enabling it, of course. -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Mark Hammack Sent: Monday, February 16, 2026 6:01 PM To: [email protected] Subject: Re: STARTTLS with AT-TLS I figured out at least part of the problem. After cleaning up syslogd, I saw the error indicating I didn't have a TLS 1.3 cipher defined. However, I had already added the TLS 1.3 ciphers so it may be that the server I'm trying to talk to had a different set. Anyway, I turned off TLS 1.3 in the AT-TLS definition and am now getting further. As to the other poster asking about "what errors", I can only say, "connection terminated". No reason, just the connection dropped out from under me. Unfortunately, syslogd had so much superfluous data in it, I missed the cipher issue the first time through (otherwise I wouldn't have posted to the list). Thanks again, Mark ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
