AEI0 indicates that a program cannot be found (either the program is not in the library or the PPT entry missing.)
If you just upgraded CTS, make sure you have all the appropriate APARs applied for CA Ideal to run under the new release of CTS. You can find this information on SupportConnect under the Compatibility section under Knowledge.
Once you have verified that all the appropriate APARs have been applied, the next item to check is the definition of module VPEHJExx (where xx is the release of CTS). This module must not be auto installed but manually defined with the following definition:
DEFINE PROGRAM(VPEHJExx) GROUP(WU11GRP) LANGUAGE(ASSEMBLER)
RELOAD(NO) RESIDENT(NO) USAGE( NORMAL )
USELPACOPY(NO) STATUS(ENABLED) CEDF(YES) DATALOCATION(BELOW)
Note: EXECKEY must be CICS.
If you are still having problems, the CICS trace from the dump is usually helpful in finding out which program cannot be found. Locate the AEI0 abend and work backwards. You should find the problem program.