Hi,
The program rfcexec (UNIX and IBM i) or rfcexec.exe (Windows) is no longer shipped together with SAP kernels 720 and 721 which might break some application scenarios. As older versions of this program are no longer compatible with SAP kernels >= 720, it is mandatory to move to a new version of these files, contained in the NW RFC SDK 720. Please refer to SAP Notes 1581595 and 1025361 for detailed instructions and further information.
pleas also see :
1768270 - RFC Error after upgrading the Classic RFC SDK Library to SAP NW RFC SDK 7.20 Library Version
Thanks and best regards,
Shi Feng