AEI0 program not found

AEI0 (PGMIDERR) means CICS could not find the program the transaction tried to LINK, XCTL or LOAD.

What it means

• The program name is not defined to CICS, not enabled, or not in the load libraries.
• It is the online equivalent of "program not found".

Common causes

• Program not defined in a PROGRAM resource (or definition not installed).
• Load module missing from the DFHRPL concatenation.
• Program name misspelled in the LINK/XCTL call.
• New version deployed to the wrong library.

How to diagnose

• Use CEMT INQUIRE PROGRAM(name) to check definition and enable status.
• Verify the load module exists in the DFHRPL libraries.
• Check the calling program for the exact name it passes.

How to fix it

• Define and install the PROGRAM resource (CEDA/CEMT).
• Place the load module in a DFHRPL library and NEWCOPY it.
• Correct the program name in the calling code.

Example: Check program definition (CEMT)

NEWCOPY loads the fresh module without a region restart.

Interview tip

• Q: How would you troubleshoot a AEI0 program not found in production?
• A: I would check the PROGRAM definition with CEMT, verify the load module is in DFHRPL, and confirm the name used in the LINK or XCTL call.

Prevention checklist

• Deployment checklist: define, install, NEWCOPY.
• Automate resource definitions with the release.