Over the past weekend a ACL script which logs the user into a CICS application stopped working.
ACL script had not changed.
Turned on the debug option and the script is completing successful, but it is not performing as it did before the system IPL.
TPX® Session Management for z/OS
Most likely this is caused by a change with the application and the signon screens being sent to TPX so that they no longer align with the existing ACL script.
First, verify the manual process for signon by using line command G, which will access the session without using the Start ACL. Pay close attention to each key used (enter, tab, etc).
Then confirm that this manual process matches the ACL code, or revise the ACL as necessary.