Communication Error, CPIC return code 020 SAP return code 223 when invoking a Function Module

Hi

I am trying to invoke a User Create Function Module in SAP ECC from DS 4.2. This was working a few days back but now the job trace logs shows bad system message. So I tried to check the SM21 log where it throws "Communication Error, CPIC return code 020 SAP return 223" error.

I tried invoking another Function Module for Partner Create which loads and returns out successfully. But the module for User Create still throws the error.

When trying to debug the function module, it was noticed the job fails before entering the module.

Could you please help me on this.

Thanks

Raghav